Buckingham Palace has announced that King Charles III has been diagnosed with cancer

Buckingham Palace has announced that King Charles is suffering from cancer.

The type of cancer was not disclosed — it was not prostate cancer, but was discovered during his recent treatment for an enlarged prostate.

The monarch began “routine treatments” on Monday and will postpone public duties while undergoing treatment, the palace said.

It added that King, 75, “is completely positive about his treatment and looks forward to returning to full public activity as soon as possible.”

No further details about the cancer's stage or prognosis were shared.

The King has privately informed both of his sons of his diagnosis and the Prince of Wales is said to be in regular contact with his father.

The Duke of Sussex, Prince Harry, who lives in the US, has spoken to his father and will travel to England to visit him in the coming days.

The monarch returned to London from Sandringham in Norfolk on Monday morning and began outpatient treatment, the palace said.

Although he will suspend his public events, the king will continue his constitutional role as head of state, which includes papers and private meetings.

When the head of state is unable to perform official duties, there is a constitutional mechanism – in which case “counselors of state” may be appointed to stand in for the monarch.

It currently includes Queen Camilla, Prince William, the Princess Royal and Prince Edward. Prince Harry and the Duke of York will no longer be known as non-working royals.

Prince William has temporarily stepped back from public engagements while his wife Catherine, Princess of Wales, recovers from “abdominal surgery”.

A week ago he underwent prostate surgery at a private hospital in London.

At the time, the palace said the treatment was a “benign” condition.

“It was during this intervention that an isolated issue of concern was noticed, which was later diagnosed as a form of cancer,” the palace said on Monday.

King chose to go public about his prostate treatment, with the aim of encouraging men to get prostate tests.

He is said to be pleased that the NHS website has raised awareness of the problem by reporting an increase in problems with prostate conditions.

For many types of cancer, the chance of getting it increases with age. UK statistics show that on average each year, more than a third (36%) of new cancers are in people aged 75 and over.

The monarch wished her a “full and speedy recovery”, as did Prime Minister Rishi Sunak, Labor leader Sir Keir Starmer and Commons Speaker Sir Lindsay Hoyle.