Syria, Venezuela and Afghanistan have not been offered invitations to the Queen’s state funeral.
The three countries join Russia, Belarus and Myanmar on the list of nations not asked to send a representative.
North Korea and Nicaragua have been invited only at ambassadorial level, joining Iran in that category.
Queen Elizabeth II will be laid to rest next Monday following a service at 11am inside Westminster Abbey that will be attended by up to 2,000 people.
All holders of the Victoria Cross or George Cross will be able to attend the Queen’s funeral.
While invitations are being sent to most nations with which the UK has diplomatic ties, the UK does not have relations with Syria or Venezuela. The political situation in Afghanistan since the Taliban swept to power a year ago means no representative has been invited from Kabul.
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On Wednesday, Prince William and Prince Harry joined King Charles and his three siblings as the Queen's coffin was moved from Buckingham Palace to the Palace of Westminster as tens of thousands watched along the Mall.
For the funeral, senior members of the Royal Family are expected to follow the coffin – just like they did for the funeral of Diana, Princess of Wales and the Duke of Edinburgh.
Heads of state, prime ministers and presidents, European royals and key figures from public life will be invited to gather in the abbey, which can hold a congregation of 2,000.
The event presents a huge logistical, diplomatic and security challenge, with practice runs taking place in the middle of the night.
Invitations were sent over the weekend to the heads of state of nations with which the UK has diplomatic relations. For most countries, that means the head of state plus one guest.
However, invites were not dispatched to the leaders of Russia – which is continuing its onslaught on Ukraine, Belarus – which has supported its neighbour in the invasion, and Myanmar – where the military seized power in a coup last year.
No guest list has been published yet, but US President Joe Biden was among the first to declare he will be flying in with his wife, Jill.
The leaders of most Commonwealth countries are expected to attend, with New Zealand Prime Minister Jacinda Ardern saying she will make the nearly 24-hour journey with a delegation of five others.
Her Canadian and Australian counterparts, Justin Trudeau and Anthony Albanese, have also confirmed their presence.
Albanese announced that he will not be travelling alone, tweeting that at Buckingham Palace’s invitation, he and Governor-General David Hurley will be accompanied by “10 Australians who have made extraordinary contributions to their communities”.
France’s Emmanuel Macron, Germany’s Frank-Walter Steinmeier, Italy’s Sergio Mattarella, Turkey’s Recep Tayyip Erdogan and Brazil’s Jair Bolsonaro are among the presidents attending, along with the European Commission’s Ursula von der Leyen.
King Felipe of Spain and his wife, Queen Letizia, are among the European royals who will attend.
Emperor Naruhito of Japan is also expected to travel to London in what would be his first overseas trip since ascending the throne in 2019.
The guest list for the Duke of Edinburgh’s memorial service could provide an idea of who else might come.
The 1,800-strong congregation featured around 30 foreign royals, including Prince Albert of Monaco, Denmark’s Queen Margrethe, and King Harald and Queen Sonja of Norway.
But it is not thought the trip will be made by Ukrainian President Volodymyr Zelensky, who took time out from organising his country’s fightback against Russian President Vladimir Putin’s forces to sign a book of condolence for the Queen.
Arrival times will vary from leader to leader, Downing Street said.
The movements of such a large number of world leaders will remain a closely guarded secret, but one report has claimed many will be forced to park at a destination outside the capital before being transported into central London on buses.
According to Politico, world leaders have been urged to fly into the UK using commercial flights and have been banned from using helicopters to get around due to limited airspace. Though President Biden is believed to have been granted special dispensation.
UK prime minister Liz Truss is not expected to hold any “formal” bilateral meetings with world leaders during the mourning period, but “there may be informal conversations that take place,”
The Queen will lie in state in Westminster Hall from Wednesday to Monday when her coffin will be taken in procession from the Palace of Westminster to Westminster Abbey for the funeral service.
Hundreds of thousands of people are expected to line the streets of the capital during the funeral.
PA contributed to this article