Britain’s Charles III has been proclaimed as king at a ceremony at St James's Palace in London on Saturday.
Charles became king immediately following the death of his mother Queen Elizabeth II, but a historic meeting formally confirmed his role on Saturday.
During the Accession Council, the King approved the day of the Queen's funeral becoming a bank holiday, although it is not known when it will take place, reports BBC.
It is the first time the historic ceremony has been televised.
The King himself was not present to begin with, but he attended the second part of the ceremony to hold his first meeting of the Privy Council, the group of senior politicians who advise the monarch.
Clerk of the Privy Council Richard Tilbrook proclaimed Charles "King, head of the Commonwealth, defender of the faith", before declaring "God Save the King".
The packed room, attended by senior politicians, judges and officials who gathered in the State Apartments of the Palace in London, repeated back the phrase.
Making his own declaration, the King said it was his "most sorrowful duty" to announce to the death of his mother.
He said: "I know how deeply you, the entire nation, and I think I may say the whole world, sympathise with me in the irreparable loss we've all suffered.
"It is the greatest consolation to me to know the sympathy expressed by so many to my sister and brothers."
The ceremony was attended by 200 members of the Privy Council, including former Prime Ministers Boris Johnson, Theresa May, David Cameron, Gordon Brown, Tony Blair and John Major.
Later, applause and cheers of "God Save the King" broke outside St James's Palace, before a crowd of thousands sang the national anthem.
It was the decision of King Charles III to allow television cameras into the Accession Council for the first time to allow the public to view proceedings.
Reuters said that the ceremony was followed by gun salutes and the reading of proclamations in London and across the four corners of the United Kingdom.
The death of 96-year-old Queen Elizabeth on Thursday after 70 years on the throne set in train long-established and highly choreographed plans for days of national mourning and a state funeral that will be held in just over a week.
Charles, 73, succeeded his mother immediately on Thursday but an Accession Council made up of hundreds of politicians, bishops and senior civil servants will proclaim his succession on Saturday at a ceremony with officials in traditional heraldic clothing.
The proclamation will be accompanied by gun salutes and heralds who travel to Mansion House in the City of London where it will be read at the Royal Exchange.
The proclamation will be read publicly in the other capital cities of the United Kingdom - Edinburgh in Scotland, Belfast in Northern Ireland, and Cardiff in Wales - and at other locations, too.
Charles is king and head of state of the United Kingdom and 14 other realms including Australia, Canada, Jamaica, New Zealand and Papua New Guinea.
King Charles names William and Kate the Prince and Princess of Wales
Britain's King Charles on Friday bestowed on his eldest son William and daughter-in-law Kate the titles of Prince and Princess of Wales, which he and his late wife Diana previously held.
Diana was a hugely popular figure who was under constant media scrutiny from her wedding onwards and the subject of a massive outpouring of grief when she died aged 36 in a car crash in 1997, five years after she and Charles separated.
A royal source said Kate appreciated the history associated with the title but would seek to create her own path as Princess of Wales.
Delivering his first speech to the nation since the death of his mother Queen Elizabeth on Thursday, Charles said he was proud to make his heir William the Prince of Wales, a title Charles had held since 1958.
"With Catherine (Kate) beside him, our new Prince and Princess of Wales will, I know, continue to inspire and lead our national conversations, helping to bring the marginal to the centre ground where vital help can be given," he said.
William and Kate, both 40, have taken on central roles within the royal family in recent years, appearing regularly in public and increasingly taking their three young children to events such as the queen's Platinum Jubilee earlier this year.
King Charles vows to serve his nation
Britain's King Charles paid a heartfelt tribute on Friday to his late "darling mama" Queen Elizabeth, and vowed to serve as monarch with "loyalty, respect and love" as she had done for more than seven decades.
In his first address to the nation, Charles paid tribute to his mother for her devotion to her family and to those she reigned over, saying her loss brought great sadness and a "sense of loss, beyond measure".
"Queen Elizabeth was a life well lived; a promise with destiny kept and she is mourned most deeply in her passing," Charles said in his address, which he delivered from Buckingham Palace with a photograph of her displayed next to him.
"That promise of lifelong service I renew to you all today."