LONDON, June 25, 2024 (BSS/AFP) - Japan's Emperor Naruhito and Empress Masako will attend a lavish banquet thrown by their host King Charles III on Tuesday as they kick off a three-day state visit to the UK.

The couple arrived in Britain on Saturday, and carried out informal engagements over the weekend, including an audience with Japanese nationals in the UK and a visit to the Thames Barrier.

But the official pomp and pageantry begins on Tuesday with a ceremonial welcome at Horse Guards Parade in London, where a guard of honour will give a royal salute and the Japanese national anthem will be played.

Naruhito, 64, and Charles, 75, will then inspect the guard of honour before taking part in a carriage procession to Buckingham Palace for lunch.

The king will take the emperor and empress to see a special exhibition of items from the Royal Collection relating to Japan, before heading to Westminster Abbey to lay a wreath at the Grave of the Unknown Warrior.

The state banquet at Buckingham Palace -- the showpiece of any state visit to the UK -- will take place in the evening.

The king, Queen Camilla, Prime Minister Rishi Sunak and Labour Party leader Keir Starmer, who is widely expected to win next month's election, will all be in attendance.

All eyes are on a possible appearance by heir to the throne Prince William's wife Catherine, who has been seen at an official engagement only once since December last year, due to cancer treatment.

Princess Anne, the king's sister, had been due to attend but she will now not be there as she recovers in hospital with concussion and minor injuries after apparently being injured by a horse.

- 'Fond memories' -

The trip will be the emperor's second official state visit since his accession to the throne in 2019, following a visit to Indonesia last year.

It was originally due to take place in 2020 and would have been the emperor's first overseas visit since he ascended to the Chrysanthemum Throne but it was delayed by the pandemic.

For Charles, it will be the third state visit he has hosted since he became king following the death of his mother Queen Elizabeth II.

Like Catherine, he was diagnosed with cancer this year but has made a limited return to public duties.

Naruhito will visit The Francis Crick Institute, the UK's flagship biomedical research centre, on Wednesday before the Lord Mayor and City of London Corporation host a banquet for him in the evening.

The emperor and empress will formally bid farewell to the king and queen at Buckingham Palace on Thursday morning before attending the "Japan: Myths to Manga" exhibition at London's V&A museum.

The emperor will later privately visit Windsor Castle to lay a wreath on the tomb of the late queen, whose funeral he attended in September 2022.

Elizabeth, whose 70-year reign began in 1952, hosted two Japanese state visits during her reign: Emperor Hirohito in 1971 and his eldest son Emperor Akihito -- Naruhito's father -- in 1998.

Speaking ahead of the trip, Naruhito said Britain's royals treated him "like family" during his time studying in England in the 1980s.

Naruhito recalled that during his two years at Oxford University, he was invited to Balmoral Castle in Scotland for a few days.

"I have very fond memories of the queen driving a car and inviting me to a barbecue... and Prince Philip showing me around by driving a carriage himself," he told a rare press conference.

The Japanese couple head to Oxford, west of London on Friday, and will fly home from near there.