Princess Mary and Prince Frederik among international royals confirmed to attend King Charles III's coronation

As King Charles III's coronation approaches, more details are emerging about the guest list for the big day.

While Prince Harry and Meghan Markle are yet to publicly confirm their attendance, some of the international royals who will be inside Westminster Abbey have been revealed.

Australian-born Princess Mary of Denmark will be there alongside husband Crown Prince Frederik, the Danish royal household has confirmed.

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"The Crown Prince couple participate in the coronation of HRH King Charles III and Queen Camilla of Great Britain," their online diary states.

The Swedish royal household has also confirmed King Carl XVI Gustaf would attend the ceremony of his third cousin, once removed, in a break from tradition.

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Usually monarchs send heirs to other monarchs' coronations but this time the King of Sweden will go along, accompanied by his daughter Crown Princess Victoria instead of his wife Queen Silvia of Sweden.

It's thought Queen Margrethe of Denmark, who is related to both of King Charles's parents – Queen Elizabeth II and Prince Philip – would have also attended were it not for her recent back surgery.

Also on Tuesday, the Japanese Imperial Household Agency confirmed Crown Prince Fumihito and Crown Princess Kiko will make a four-day trip to London for the ceremony, Kyodo News reported.

"Per custom, Emperor Naruhito does not attend foreign royal coronations, leaving his younger brother to attend in his stead," they wrote.

The royals will stay in Claridges Hotel, it's reported, and they'll attend "a royal reception on the afternoon of May 5" – although that portion of the coronation program is yet to be announced by Buckingham Palace.

Prince Albert of Monaco and his wife Princess Charlene had already confirmed their attendance to the event during an interview earlier this year.

"I'm certain that it's going to be an incredible ceremony and a very moving one," the royal previously told People magazine about the big day.

"We've maintained contact since His Majesty became King, but I haven't talked to him personally since the Queen's funeral."

"I'm certain His Majesty will add his own 'personal touches' to the ceremonies," the 65-year-old added.

Spain's King Felipe is also set to attend his distant cousin's coronation along with wife Queen Letizia, the Spanish royal household has confirmed according to local media.

On Saturday Buckingham Palace announced more than 850 community and charity representatives from across the UK have also been invited to witness the King's coronation ceremony.

There will also be 450 British Empire Medallists amongst the more than 2000 guests who will form the congregation in Westminster Abbey.

This is considered much smaller than Queen Elizabeth II's 1953 coronation, held in the same place, which had 8251 people in attendance.

Also to help keep the guest list down, it's been reported that Buckingham Palace has given only Prime Minister Rishi Sunak a plus one on his invite. All other UK Cabinet ministers will not be allowed to bring their partners or a guest, according to Daily Mail.