King Charles and Queen Camilla met with Pope Francis this afternoon in secret meeting

and paid a private visit to Pope France at the Vatican this afternoon, Buckingham Palace announced late last night. It is understood the visit was only confirmed on Wednesday morning and was subject to the Pope's health.

A spokesperson said: "Their Majesties were delighted The Pope was well enough to host them - and to have had the opportunity to share their best wishes in person."

During the 20 minute meeting at the Casa Santa Marta the pointiff who a happy anniversary. Gifts were exchanged and a picture of the meeting will be released tomorrow morning.

It is understood that the Holy Father issued the invitation for a private audience with the King and Queen after .

Pope Francis, 88, returned to the Vatican on March 23 after .

During his hospitalisation and doctors say he needs at least two months of rest at his residence.

On Sunday he made a surprise appearance at St Peter's Square, briefly appearing in a wheelchair with an oxygen tube under his nose. "Hello to everybody," he said, waving to cheering crowds. "Happy Sunday to all of you, thank you very much."

The King and Queen are understood to have visited the Pope after they returned from the Italian Parliament this afternoon.

Discussions continue about an official state visit to the Vatican.