The King has been diagnosed with a form of cancer, Buckingham Palace has announced.

The Palace confirmed the disease, which is not prostate cancer, was discovered while the King was being treated in hospital for an enlarged prostate.

The King has started a schedule of regular treatments, but has been advised to postpone his public-facing duties.

The Palace declined to confirm the type of cancer.

He will carry on working behind the scenes on state business and official papers, and returned from Sandringham to London on Monday to commence treatment as an out-patient.

Buckingham Palace said in a statement: “During The King’s recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted.

“Subsequent diagnostic tests have identified a form of 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.

“Throughout this period, His Majesty will continue to undertake State business and official paperwork as usual.

“The King is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure.

“He remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible.

“His Majesty 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.”

Charles, 75, was discharged from the London Clinic a week ago after undergoing treatment on an enlarged prostate.

The shock news is the latest health scare to hit the royal family at the start of 2024, coming after the King’s hospital stay, the Princess of Wales’s major abdominal surgery and Sarah, Duchess of York’s diagnosis of skin cancer.

Buckingham Palace announced on January 16 that the King was to have treatment for an enlarged prostate, but that the condition was benign.

The Palace announced the King’s cancer diagnosis at 6pm on Monday.

Charles, who acceded to the throne just 17 months ago, was last seen on Sunday when he attended church in Sandringham.

Since the news broke, well wishes for the King have poured in from across the political spectrum.

Prime Minister Rishi Sunak said on X: “Wishing His Majesty a full and speedy recovery.

“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.”

Labour leader Sir Keir Starmer tweeted: “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.”

Liberal Democrat leader Ed Davey posted: “The Liberal Democrats join the rest of the nation in wishing a full and quick recovery to His Majesty.”

The King was also praised for making his diagnosis public.

Health and Social Care Secretary Victoria Atkins wrote on X: “My thoughts are with King Charles and the whole Royal Family.

“His decision to share his diagnosis to assist public understanding for all those affected by cancer is commendable.

“Wishing His Majesty the very best and look forward to seeing him resume his public duties.”

Shadow health secretary Wes Streeting, who received treatment for kidney cancer in 2021, said: “One in two of us will develop cancer during our lives, but millions more are affected when someone they love is diagnosed with cancer.

“Sending best wishes to His Majesty for his treatment and to his family as they support him throughout.”

Commons Speaker Sir Lindsay Hoyle told MPs: “I know the whole House will wish to join me in expressing our sympathies with His Majesty the King following the news announcement this evening.

“Our thoughts are, of course, with His Majesty and his family, and we’d all wish to send him our very best wishes for the successful treatment and a speedy recovery following tonight’s news.”

Mr Sunak’s immediate predecessors in No 10, Boris Johnson and Liz Truss, also sent their best wishes to the King, with Mr Johnson saying: “The whole country will be rooting for the King today.”

Welsh First Minister Mark Drakeford, Scottish First Minister Humza Yousaf, Northern Ireland’s First Minister Michelle O’Neill and deputy First Minister Emma Little-Pengelly also sent get-well wishes.

The Palace said the disease was found while the King was being treated in hospital for an enlarged prostate, but that it is not prostate cancer.