Although she did not specify what kind of cancer, she explained she has been receiving chemotherapy treatment.

The Princess was last seen on Christmas Day with her children and husband Prince William before undergoing what was officially described as “preplanned” abdominal surgery.

“At the time, it was thought that my condition was non-cancerous. The surgery was successful, however, tests after the operation found cancer had been present,” the Princess of Wales said.

“My medical team therefore advised that I should undergo a course of preventative chemotherapy and I’m now in the early stages of that treatment.

“This of course, came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family.”

The Princess of Wales said it has taken some time to recover from surgery to be able to start chemotherapy treatment.

“But most importantly it has taken us time to explain everything to George, Charlotte, and Louie in a way that’s appropriate for them and to reassure them that I’m going to be ok,” she explained of her public absence.

“As I’ve said to them, I am well and getting stronger every day by focusing on the things that will help me heal in my mind, body, and spirits.

“Having William by my side is a great source of comfort and reassurance too, as is the love support, and kindness that has been shown by so many of you. It means so much to us both.”

The 42-year-old said the last few months have been “incredibly tough.”

“But I’ve had a fantastic medical team who’ve taken great care of me, for which I’m so grateful,” she said.

“For now I must focus on making a full recovery. At this time, I’m also thinking of all those whose lives have been affected by cancer. For everyone facing this disease in whatever form please do not lose faith or hope. You are not alone.”

–With files from Andrew Osmond