King Charles and Queen Camilla have had a private meeting with Pope Francis at the Vatican where he wished them a happy 20th wedding anniversary.

In a statement released by Buckingham Palace, the King and Queen said they were "delighted the Pope was well enough to host them – and to have had the opportunity to share their best wishes in person".

The meeting took place on the third day of their state visit to Italy and ahead of a state banquet in Rome on Wednesday evening.

It is understood the meeting was only confirmed on Wednesday morning. It came after previous plans for the couple to meet the pontiff in a state visit to the Vatican were postponed because of the Pope's ill health.

The meeting took place on Wednesday afternoon at the Vatican's Casa Santa Marta, where Pope Francis has been convalescing since being released from Gemelli Hospital.

A photograph of the meeting, which lasted 20 minutes, was released by the Vatican on Thursday morning.

The Royal Family X account posted it along with the caption "Che occasione speciale", which translates as "what a special occasion".

"The King and Queen were deeply touched by the Pope's kind remarks about their 20th wedding anniversary and honoured to be able to share their best wishes to him in person," the statement added.

According to the Vatican, the Pope is showing signs of gradual improvement and he "reciprocated" the King's "best wishes for a speedy recovery of his health".

This was a reference to the Pope offering his own best wishes, after the King recently suffered side effects from his cancer treatment.

There was also an exchange of private gifts between Pope Francis and the royal visitors.

The King and Queen have been enjoying a warm welcome on their state visit to Italy, but it was a trip that originally had a significant focus on visiting the Vatican and planned events such as a service at the Sistine Chapel.

That had been no longer been possible after the serious health problems of Pope Francis – but with his health improving the King and Queen had the opportunity for a brief meeting.

After visiting the Pope, King Charles and Queen Camilla spent their wedding anniversary evening at a state banquet in Rome hosted by the President of Italy Sergio Mattarella.

The King joked to his Italian hosts at the Quirinale Palace about laying on such a spectacle for their anniversary.

"I must say it really is very good of you, Mr President, to lay on this small romantic, candle-lit dinner for two..," the King told the banquet.

There were 150 guests at the dinner, including the singer Andrea Bocelli, chef Giorgio Locatelli, hotelier Rocco Forte and UK Foreign Secretary David Lammy.

Earlier in the day, at the Italian Parliament, Queen Camilla had worn the same outfit she had worn at her civil wedding ceremony in 2005.

The ivory silk dress designed by Anna Valentine had been "repurposed" to wear again for this anniversary day.

The King's speech at the state banquet, at the Italian presidential palace, touched on a mix of comic and serious themes about the long relationship between the UK and Italy, back to the ancient Romans.

"I for one, have never asked that question, made famous by Monty Python, 'What have the Romans ever done for us?'," the King joked.

"We see their imprint on what they knew as Britannia every day – from London to Carmarthen, from York to Hadrian's Wall."

But he also warned that "we are living in a very precarious and fragile world" and there was a need to stand up for "values and the liberty we hold so dear".

"In difficult times, friends stand together," he told his audience, in a speech that once again referenced the conflict in Ukraine.

The menu for the state banquet, in the splendour of the medieval palace, included bottoni pasta with aubergine caponata, salt encrusted sea bass, fried artichokes and roast potatoes.

That was followed by a fior di latte ice cream cake with raspberries.

This was the King's second speech of the day, as earlier he had become the first UK monarch to address both houses of the Italian Parliament.

The King received a standing ovation from Italy's lawmakers, in their ornately decorated chamber in the Palazzo Montecitorio, with a rallying call to defend shared values and the need to reinforce the military partnership between the UK and Italy.

"We are both European countries," he said, standing in front of the Italian and European Union flags.

He welcomed that the UK and Italy "stood by Ukraine in her hour of need", but warned that images of wars were now reverberating across the continent.

"Our younger generations can see in the news every day on their smartphones and tablets that peace is never to be taken for granted," said the King.

Such threats meant it was important that "Britain and Italy stand today united in defence of the democratic values we share", he told Parliament.

Delivering some of the speech in Italian, he spoke of the long history between the UK and Italy, going back to the ancient Romans arriving on Britain's "windswept shores".

As head of the Commonwealth, he also spoke of the role of Canadian troops in helping to liberate Italy in the Second World War.

The speech went down well with the assembled Parliamentarians – with the applause so long at one point that an Italian official began to thank him, assuming that the King had finished.

The King began the day by meeting Italy's Prime Minister Giorgia Meloni, receiving a ceremonial red-carpet welcome at the Villa Doria Pamphili, on the outskirts of Rome.

The Italian public has given a warm reception to the royal couple on their trip to Italy, including outside the Colosseum, when the King and Queen posed for photos near the ancient site of the Temple of Venus.

There were calls of "Carlo" – Italian for Charles – from crowds waiting to see the royal visitors and local media also seemed interested by their car, the claret coloured State Bentley.

The Royal Family's official X account marked the wedding anniversary by posting a video which showed guards playing a version of Madness's 1981 hit It Must Be Love.