King Charles III and Queen Camilla arrive to attend a Sunday church service at St Mary Magdalene Church in Sandringham, England, on Sunday. AP

Britain’s King Charles has been diagnosed with a form of cancer and the 75-year-old will postpone public-facing duties while he undergoes treatment, Buckingham Palace said on Monday.

Charles, who became king in September 2022 following the death of his mother Queen Elizabeth, is “wholly positive” about his treatment and looks forward to returning to full public duty as soon as possible, the palace said.

Charles spent three nights in hospital last month where he underwent a corrective procedure for an enlarged prostate. The palace said a separate issue of concern had been spotted during the hospital visit, but did not given any further details beyond saying the king had a “form of cancer.” A royal source said that it was not prostate cancer.

“His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties,” the palace said. “Throughout this period, His Majesty will continue to undertake State business and official paperwork as usual.

The Palace added that the king “has chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer.”

Prince Harry, King Charles’ younger son, has spoken with his father about the cancer diagnosis and will travel to the UK to see him in the coming days, a source close to the prince said.

Harry now lives in California with his American wife Meghan and their two children after the couple stepped down from royal duties in 2020.

The news comes just days after Charles and his daughter-in-law Kate left the same hospital where they had both undergone planned treatments.

Kate, the Princess of Wales and wife to heir to the British throne Prince William, spent two weeks in hospital following abdominal surgery.

British Prime Minister Rishi Sunak sent his best wishes to the King on X. “I have no doubt he’ll be back to full strength in no time and I know the whole country will be wishing him well,” he said.

“On behalf of the Labour Party, I wish His Majesty all the very best for his recovery. We look forward to seeing him back to swift full health,” opposition leader Keir Starmer said.

On behalf of Londoners I wish His Majesty a speedy and full recovery. I look forward to his return to full health as soon as possible,” Sadiq Khan tweeted.

Reuters