Venezuela said Tuesday it had arrested a fourth U.S. citizen over what it claims was a plot to assassinate President Nicolás Maduro in the aftermath of elections the opposition claims he stole.

The American was arrested in Caracas after “taking photos of electrical installations, oil facilities, military units,” Interior Minister Diosdado Cabello said. Three other U.S. citizens, two Spaniards and a Czech have also been arrested in Venezuela in recent weeks.

Cabello told the National Assembly the man was “part of the plot against Venezuela, the plot against our country,” which he said included a plan to “assassinate President Nicolás Maduro” and others, including himself.

On Saturday, Cabello announced the arrest of the other six foreigners, whom he said worked for intelligence agencies and the Venezuelan opposition.

One of the Americans was identified as an U.S. Navy sailor detained in Venezuela earlier this month. A State Department spokesperson told CBS News in a statement Saturday that the Biden administration could confirm the detention of the sailor.

Washington, Madrid and Prague, who have denied involvement in any plot against Maduro, on Monday demanded information from Venezuela about their citizens.

Maduro said Monday they had all “confessed.”

Venezuela has been engaged in a war of words with the U.S., which recognized Venezuelan opposition candidate Edmundo González Urrutia as the winner of the election. Washington last week announced new sanctions against 16 Venezuelan officials, including some from the electoral authority, for impeding “a transparent electoral process” and not publishing accurate results.  

Tensions between Caracas and former colonial power Spain rose sharply after González Urrutia, 75, went into exile in Spain a week ago, after being threatened with arrest.

Last week, Caracas recalled its ambassador to Madrid for consultations and summoned Spain’s envoy to Venezuela for talks after a Spanish minister accused Maduro of running a “dictatorship.” Venezuela was also angered by Spanish Prime Minister Pedro Sánchez’s decision to meet with González Urrutia and warned Spain against any “interference” in its affairs.