What was not disclosed at the time — either to his readers or the fellow journalists who turned to Seipel as a Putin pundit — is that one of Russia’s wealthiest oligarchs had directed hundreds of thousands of dollars to underwrite Seipel’s book, according to secret corporate documents obtained by an international consortium of news organizations, including The Washington Post.

The revelations suggest that Russia has continued to rely on an old-fashioned tactic — cultivating opinion-makers with an eye to generating positive news coverage — to promote its worldview overseas.

In his interview that day, the Hamburg-based author expounded that the Russian president “is considered the epitome of evil in the United States.”

Democrats, Seipel said, liked to blame Putin for Donald Trump’s 2016 election victory, while Republicans had designated him as the external enemy “who can also be blamed for [their] own mistakes.”

Seipel’s German publisher bills him as “the only Western journalist to have direct, personal access” to Putin. The award-winning reporter spent extensive time with him in Russia for a 2012 documentary and later interviewed Putin for the German public broadcaster ARD. In 2015, Seipel published his first book on Putin, a biography, following it two years ago with “Putin’s Power: Why Europe Needs Russia.”

Newly revealed financial documents indicate that a shell company connected to businesses owned by Russian steel and banking magnate Alexei Mordashov promised to pay Seipel about 600,000 euros, then roughly equivalent to $730,000, to support his work on “Putin Power.” One document pertaining to the deal also references an earlier agreement for a “Putin biography.”

The discovery by German investigative newsroom Paper Trail Media and its partners Spiegel and ZDF provides a rare look into Russian efforts to influence overseas opinion and shape narratives of Putin and the Kremlin through traditional foreign media.

A former editor and foreign correspondent for the German magazines Stern and Der Spiegel, Seipel scored the world’s first televised interview with national security leaker Edward Snowden in 2014 and has won several top television prizes, including the German equivalent of an Emmy.

In written responses to questions from Paper Trail Media and The Washington Post, Seipel acknowledged receiving support from Mordashov, though he did not answer questions about specific monetary amounts or any other form the oligarch’s “sponsorship” might have taken.

He said Mordashov’s support was exclusively for his book projects and denied ever receiving money from third parties to fund his films or TV interviews.

And Seipel defended his editorial independence and said that his books contain no factual errors. “This is the central point for me as a journalist,” he said.

Seipel did not answer questions about why he did not disclose Mordashov’s patronage to his publisher.

The documents revealing the secret patronage come from a leak of 3.6 million files from seven financial service providers — six in Cyprus, one in Latvia. The findings are part of Cyprus Confidential, a cross-border investigation led by the International Consortium of Investigative Journalists and Munich-based Paper Trail Media that looks at how the Russian elite have hidden their assets within the European Union, even in the face of international sanctions.

Those files include a “deed of sponsorship” signed in 2018 between Seipel and a shell company affiliated with businesses owned by Mordashov, who has since been sanctioned by the European Union for his ties to Putin.

In his response to Paper Trail, Seipel quoted that same document to underscore his independence — specifically, a clause holding that the author has “no obligation” to the sponsor “with respect to the content” of the book nor even whether it is published.

“I worked on my book projects for eight years to get access to information,” he told The Post in a separate email exchange, describing “dozens” of trips to Russia and research conducted in Washington, at the United Nations and Berlin. “A period of time and effort that is not calculated by publishers. And when it came to support for my work, I always made clear legal boundaries that guaranteed my independence.”

His publisher, Hamburg’s respected Hoffmann und Campe, said in a statement that it had no previous knowledge of any “sponsorship income” related to the two Seipel books it has released.

“If these [claims] prove to be true, we reserve the right to take further steps in connection with the books,” the statement added. Hoffmann und Campe said it currently has no plans to publish more books by Seipel.

Much of the recent conversation about Russian propaganda efforts has focused on its covert online trolling operations. But such projects are just “one cog in the influence machine, and arguably not as important as they used to be,” said Darren Linvill, a Clemson University professor who studies disinformation.

Meanwhile, Russia has continued to spend heavily on more-traditional media outreach. This includes such state-sponsored platforms such as RT (formerly Russia Today), whose Spanish-language news service was the fast-growing news outlet in Latin America before the invasion of Ukraine, according to an analysis by Linvill.

RT was Russia’s answer to CNN. Now its pro-Putin spin on Ukraine is sparking new outrage.

And punditry is another way for Russia to get its story out there. Around the world, there is a cadre of commentators and online influencers who “don’t really hide the fact that they’re pro-Russian,” Linvill added. While there’s some evidence to suggest that the Kremlin might support them, “you never see a clear line” to demonstrate they are receiving payment from Russia, he said.

“Just because you’re paying somebody doesn’t mean they don’t believe what they’re saying,” he noted. “They’re not mutually exclusive categories.”

In Germany, several key figures in civic and political life had long taken a sympathetic stance toward Russia before the invasion of Ukraine — thanks in part to Putin, a German speaker who served in Dresden for the KGB in the 1980s and has worked to nurture close ties within the country.

German think tanks and foundations were awash in Russian cash. Russian companies, such as the energy giant Gazprom, sponsored athletic teams, music festivals and art exhibitions in Germany. Some German leaders, like former chancellor Gerhard Schröder, who encouraged reliance on Russian energy, were labeled as Putinversteher or “Putin understanders,” eager to justify or explain Putin’s actions.

“We had this long tradition of trying to understand Putin and not being too harsh with him,” said Tanjev Schultz, a former reporter and journalism professor at Johannes Gutenberg University in Mainz, Germany. “The same could be said about the media scene.”

But after the invasion of Ukraine — which German Chancellor Olaf Scholz declared a Zeitenwende, or turning point, for Germany’s security strategy — opinion soured toward Russia.

“The main voices in journalism in the big media organizations are now totally clear about that, that this dictatorship of Putin is just all wrong, and there’s really a big wave of solidarity when it comes to Ukraine,” Schultz said

Russian state-controlled media outlets such as RT and Sputnik have been shuttered in Germany, and the Putin-promoted cultural and academic exchanges have ground to a halt. But Germany remains a focus of Russian espionage and influence operations, Western intelligence officials say.

In April, The Post reported that the Kremlin was secretly attempting to forge an antiwar alliance between the far-right and the far-left in Germany and stoke protests against the government. The ultimate goal, documents showed, was to end German support for sanctions on Russia and military aid to Kyiv, which amounted to more than 5 billion euros in 2023.

Earlier in his career, Seipel reported on the Kosovo war, the nuclear industry and a Volkswagen corruption scandal. He first met Putin more than a decade ago while filming a documentary about the energy industry.

“That’s where the idea came from,” Seipel told an interviewer in February. “‘Okay, this guy is interesting, someone should actually make a documentary about him.’”

Seipel told the interviewer that he had several requirements of Putin’s team: He needed direct access to Putin for several months, and insisted that Putin would not be allowed to see the footage ahead of the film’s release.

The resulting 2012 documentary, “I, Putin,” gave viewers an unusually personal view. Seipel got the Russian leader to talk about his humble beginnings in St. Petersburg; he followed Putin on a hunting trip and to judo practice and watched him swim laps in a pool. (In one memorable scene, a dog wanders over to lick Putin’s ear as he pulls himself out of the water in small swim shorts.)

In terms of access, it was a coup. “The powerful Russian politician has never been the subject of such an intimate portrayal on film, and certainly not from the perspective of a Western journalist who can edit the footage as he sees fit,” raved one review in Spiegel.

“I, Putin” was aired by German public broadcaster ARD, a widely watched and reputable public media outlet that receives taxpayer funds, where Seipel previously worked. It was also nominated for a top German documentary prize.

Seipel’s 2015 follow-up book raised more eyebrows. Some critics thought he allowed Putin too much latitude to air his positions. Seipel appeared alongside Putin for the book’s Russian release, where the Russian president said he believed governments should allow information to flow freely “even if they don’t like some of the information,” German newspaper Frankfurter Allgemeine Zeitung reported at the time.

In 2021’s “Putin’s Power,” Seipel offered a window into Putin’s view of Russia’s position in the world. (“Putin regards the attempt to separate Ukraine economically from Russia as a political maneuver against his country.”) Some critics found Seipel’s take overly credulous. “In his view, there is no evidence of Russia’s interference in the 2016 American presidential election campaign,” wrote the journal of the German Council on Foreign Relations. “It is not Russia, but the USA that is the front-runner in wiretapping and spying.”

In his response, Seipel said that his books “have given rise to lively discussions and ideological battles.”

The newly revealed documents show that in 2018, Seipel received a promise of financial support from De Vere Worldwide Ltd., a British Virgin Islands-based company.

Under that deed of sponsorship signed in 2018, De Vere agreed to pay Seipel 600,000 euros and “reasonable logistical and organizational support during his research in Russia” for a book he was writing on the “political environment in the Russian federation,” to make it “available to a wider audience.”

Other corporate documents and banking instructions uncovered by Paper Trail Media and its partners, Spiegel and ZDF show that two companies owned by Mordashov loaned a total of roughly 600,000 euros to De Vere in 2018 and 2019. De Vere shortly after directed similar amounts to be paid to Seipel as part of the sponsorship, according to banking instructions.

The document shows De Vere Worldwide Ltd. is owned by a manager for another Mordashov-owned company. A lawyer working for Mordashov’s steel and mining company Severstal signed the 2018 sponsorship deed as a witness.

In his written response to questions, Seipel said it was “false” to suggest that he was commissioned to write the book. He said he had decided on his own two years earlier to write a book that “took the Russian perspective into account,” he said, “because of the escalating political confrontation after the Crimean annexation.”

Mordashov — who is estimated by Forbes to be worth more than $20 billion — was among the oligarchs sanctioned in 2022 by the European Union for profiting from Putin’s regime and the invasion of Ukraine. The sanction announcement noted that his Severgroup investment company is a shareholder in a bank favored by Putin’s allies as well as pro-Kremlin TV stations that promoted the destabilization of Ukraine.

A spokesperson for Mordashov denounced the sanctions as “unfounded and unjust” and denied that Mordashov and his companies have run afoul of European or Russian laws.

The spokesperson did not respond to questions about Mordashov’s sponsorship of Seipel’s books.

In his written responses, Seipel acknowledged that Mordashov is “a lobbyist for his own interests,” such as his love of Russia. But the author suggested that he had remained unswayed by the oligarch’s point of view. “Proximity/nearness does not automatically mean co-optation,” he wrote. “Politics tries to exploit journalists, and journalists try to exploit politicians. This is no different in Moscow, Washington or Berlin.”

Seipel called his sponsor “a man of influence and knowledge” whose standing in Russian society and contacts in the political scene offer “an asset to any research.” He added: “It’s not about hotel rooms or flights that he never booked for me.”

The writer has increasingly come under scrutiny in recent years, with some critics suggesting Seipel has been compromised by his closeness to Putin. In interviews following his 2021 book release, one radio host pressed him on this.

“You need a certain level of nearness to basically find something out,” Seipel replied. “The question is, at what point do you identify [with the subject]? At what point are you being, so to speak, instrumentalized without noticing? And how flattered could you basically be, that a powerful person, so to speak, is welcoming you. … That is always a danger. But that is fundamentally a danger in our job.”

The radio host asked if Russia had ever directly or indirectly paid him.

“Have you lost the plot?” Seipel responded, incredulously. “No!”

When asked about that exchange for this story, Seipel said that he believed the question referred to a payment from the Russian president, and “I am not paid by him.”

Seipel last spoke with Putin in September 2022, he told an Austrian interviewer in February. He said he was writing yet another book — this time, about the war in Ukraine.

Carina Huppertz and Sophia Baumann contributed to this report.