Buckingham Palace on Tuesday revealed the diagnosis for the 75-year-old monarch.

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

“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.

The King and Queen Camilla were expected to tour Australia in late 2024.

Prime Minister Anthony Albanese said he would send a message to the palace on behalf of the nation.

“We have invited King Charles to visit Australia and we sincerely hope that that is able to occur,” he said on Tuesday.

“We hope King Charles has a speedy recovery and a return to his duties as soon as possible.”

Following the diagnosis, Opposition Leader Peter Dutton urged men not to delay a visit to the doctor.

“We wish every best wish to King Charles … he’s a stoic individual,” he said.

“There’s a message the palace wants to get out as well … make sure you go and have a check-up because early detection is important.”

Australian Monarchist League chairman Eric Abetz said the nation was looking forward to a possible royal trip.

“It will be a real pity for all those who were looking forward to that very exciting prospect of having the King of Australia come and be here with us,” Abetz said.

“Let’s see how this develops and let’s hope the medical team for King Charles can deal with this matter as quickly as possible.”

King Charles spent three nights in hospital last month after undergoing a corrective procedure for a benign enlarged prostate, when a separate issue of concern was noted.

The Press Association cited a source saying Prince Harry, who resides in the United States, had spoken with the King about his diagnosis.

“The duke did speak with his father about his diagnosis. He will be travelling to UK to see His Majesty in the coming days,” the source close to Harry said.

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

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

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

– with AAP