Queen Elizabeth's funeral on Monday will be attended by around 500 guests representing nearly 200 countries and territories, a British foreign office source said on Friday.
Nearly 100 presidents and heads of government and over 20 royals will attend, the source said.
The guests include the Crown Prince of Bahrain, the Amir of the State of Qatar and the Sultan of Oman. The Saudi royal family will also be represented, the source said.
King Charles III and his three siblings stood guard around their mother Queen Elizabeth II's coffin on Friday in solemn vigil honouring Britain's longest-serving monarch.
The new king, Princess Anne, and Princes Andrew and Edward mounted the guard in silence around her flag-shrouded casket as members of the public, who had queued for hours, continued to file past.
The "Vigil of the Princes", with the royals all in ceremonial naval uniform, formed an emotionally-charged moment in London's mediaeval Westminster Hall, where Queen Elizabeth's coffin is lying in state ahead of Monday's funeral.
Her children stood with their heads bowed for 12 minutes as other members of the royal family including Queen Consort Camilla watched on and the public paid their own last respects.
King Charles and his siblings mounted a similar vigil at St Giles' Cathedral in Edinburgh before the coffin was flown to London.
The Vigil of the Princes first took place in Westminster Hall in 1936 for king George V. His four sons, including Queen Elizabeth's father, stood guard.
Prince William and his brother Prince Harry will lead the Queen's grandchildren in a similar vigil on Saturday evening.
Members of the public have been facing waits of up to 24 hours to file past the coffin.
Agencies