Pope Leo XIV (left) bids farewell to Britain's King Charles III (right) during the British king's state visit to Vatican City. (EPA Images pic)LONDON: Britain's King Charles III is writing to Pope Leo XIV after the leader of the world's Catholics had a cancerous tumour removed from his lung, a royal source said Wednesday.

Charles, who is the head of the Church of England, would write privately to the pope to pass on his best wishes, the source said.

He and Queen Camilla met with Leo last year at the Vatican shortly after he was elected as pontiff, becoming the first American pope.

Part of the pope's right lung was removed in Tuesday's operation and the leader of the world's 1.4 billion Catholics is awaiting the results of tests to determine if the cancer has spread.