The palace said King Charles, 75, who was crowned in September 2022 following the death of his mother Queen Elizabeth, had begun a series of treatments, adding that he was looking forward to returning to full-time duties as soon as possible.

News of King Charles' cancer comes after he spent three nights in hospital last month, where he underwent a procedure to treat benign prostatic hyperplasia.

Buckingham Palace said another worrying issue was discovered during that hospital stay, but did not provide any further details beyond saying that tests showed the King had a "form of cancer".

“No further details are being shared at this stage, other than to confirm that His Majesty does not have prostate cancer,” the palace said. “During this time, His Majesty will continue to undertake State duties and official paperwork as usual.”

Chancellor Rishi Sunak sent his best wishes to the King. "I am sure he will be back to full health very soon and I know the whole nation will be wishing him well," he said.

The leaders of Australia and Canada have expressed their best wishes and hopes for the king's speedy recovery, while US President Joe Biden said: "Jill and I join the people of the United Kingdom in praying for His Majesty the King to make a speedy and full recovery."

Hoang Anh (according to Reuters, AP)