Also on Friday, the Pope phoned Russian President Vladimir Putin from hospital to urge a ceasefire in the Russian-occupied Ukrainian city of Oleshky, where access to food and water has been cut off for thousands.

“The fact that he accepted the call and spoke with the Pope may, I hope, be a sign that the Pope’s request will indeed be carried out,” said Cardinal Pietro Parolin, the Vatican’s secretary of state.

Without mentioning a ceasefire, the Kremlin said: “The Vatican’s intention to help create the conditions necessary to ensure the safety of the town’s population and to organise vital supplies has been supported.”

It added: “It has been agreed to co-operate on this matter.”

The UN high commissioner for human rights, Volker Turk, made a similar plea to address what he described as a “desperate” situation in Oleshky.

The Pope’s doctors said on Friday that tests had shown “a steady improvement in his general condition” since his surgery.

His doctors said that a chest X-ray indicated “good recovery of the operated lung”.

The whole lower lobe of the Pope’s right lung was removed “to ensure the procedure was radical”, the Vatican said following the surgery.

“After the operation, the Pope awoke normally and returned after a brief period of observation to his room,” it said earlier, before he spent a “peaceful night” at the hospital.