King Charles III on Monday began a state visit to Italy in which he will address parliament and tour the Colosseum, although an audience with Pope Francis was postponed over the pontiff's ill health.

The four-day trip comes 10 days after Charles, 76, was briefly admitted to hospital after experiencing temporary side effects from his cancer treatment.

Charles and his wife, Queen Camilla, who will celebrate their 20th wedding anniversary while in Rome, touched down at the capital's Ciampino Airport at around 5:20 pm (1720 GMT).

They descended from the airplane in bright sunshine onto a red carpet, and were greeted by dignitaries and a guard of honor. The king waved and smiled as the royals were driven away. 

Charles knows Italy well, having already made 17 official visits, although this is his first since taking over as monarch following the 2022 death of his mother, Queen Elizabeth II.

The king, who is also head of the Protestant Church of England, had been due to meet Pope Francis but the audience was postponed due to the Catholic leader's ill health.

Francis, 88, has been ordered to spend at least two months convalescing after a life-threatening bout of pneumonia — although he made a surprise appearance at the end of a mass at the Vatican on Sunday.

'Reset' relationships

Rome authorities have warned of disruptions for locals due to tight security and roadblocks around the city, notably when Charles and Camilla visit the Colosseum on Tuesday.

The couple plan to lay a wreath at the Tomb of the Unknown Soldier and watch a joint flypast over Rome by Italy's "Frecce Tricolori" air force aerobatic team and Britain's "Red Arrows".

Charles is due to meet Italy's Prime Minister Giorgia Meloni and President Sergio Mattarella.

The king -- who is being joined on the trip by UK Foreign Secretary David Lammy -- is also set to become the first British monarch to address a joint sitting of the Italian parliament.

Britain's ambassador to Italy, Edward Llewellyn, said the state visit came at a "key moment" as the UK seeks to "reset our relationships with European partners" five years after Brexit.

"This visit will inject further momentum to drive that cooperation across the board but especially on defence, on sustainability, on clean energy and our cultural ties," he said on Monday.

Dante's tomb

The king and queen were married on 9 April 2005, after a long affair during Charles's marriage to the late Diana.

They will mark their 20th anniversary on Wednesday at a state banquet at the 16th-century Palazzo Quirinale in Rome, and have reportedly asked for a vegetarian menu, according to Italian media.

During their trip, the royals will visit the historic city of Ravenna in northern Italy.

They will attend a reception marking the 80th anniversary of the region's liberation from Nazi occupation by Allied forces on 10 April 1945.

And they will view the tomb of poet Dante Alighieri and sample traditional food from the northern Emilia Romagna region, as well as meeting local farmers.

"Their visit will strengthen the closeness between our nations in a way that only they can," Ambassador Llewellyn said.

"Their love for Italy and all things Italian, the things Italians cherish -- culture, food, heritage -- resonate very, very deeply here."

'Minor bump'

Charles announced he had cancer in February 2024, without specifying which kind, but resumed his activities at the end of April.

While continuing to receive treatment, he gradually ramped up his duties, making several foreign trips including to Australia and Samoa in October.

Officials said his recent hospital stay, of a few hours on 27 March, was a "minor bump" in his medical journey, and he resumed engagements on 1 April.

Charles' daughter-in-law Catherine, Princess of Wales, was also diagnosed with cancer last year but said in January she was in remission.