Rishi Sunak has wished King Charles a "full and speedy recovery" from cancer.
Buckingham Palace has confirmed that the 75-year-old monarch has been diagnosed with "a form of cancer" following a "corrective procedure" for an enlarged prostate, and the UK Prime Minister has now taken to social media to send his best wishes to the King.
Sunak, 43 - who has served as the UK's Prime Minister since 2022 - wrote 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."
Sir Keir Starmer, the leader of the Labour Party, has also sent his best wishes to the monarch.
The 61-year-old politician wrote on X: "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."
Elsewhere, Emma Little-Pengelly - Northern Ireland's Deputy First Minister - said that she'll "keep him and his family in [her] prayers".
She said: "I would like to wish His Majesty, King Charles all the very best for his treatment.
"I, like many people throughout Northern Ireland, will keep him and his family in my prayers."
Charles has already begun his cancer treatment and Buckingham Palace has confirmed that he will "continue to undertake State business and official paperwork as usual".
In a statement, the Palace added: "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."