The Duke of Edinburgh, the longest serving royal consort in British history, has died in Windsor Castle at the age of 99.
"It is with deep sorrow that Her Majesty The Queen announces the death of her beloved husband, His Royal Highness The Prince Philip, Duke of Edinburgh," the statement said.
"His Royal Highness passed away peacefully this morning at Windsor Castle. Further announcements will be made in due course.
"The Royal Family join with people around the world in mourning his loss."
The duke, who was a constant presence at Queen Elizabeth II's side for decades, was in hospital for a month after being admitted as a precautionary measure on February 16.
He was discharged on March 16 after treatment for an infection and successful surgery for a pre-existing heart condition.
A Greek prince, he married Elizabeth in 1947 and played a key role in modernising the British monarchy in the post-Second World War period.
Behind the walls of Buckingham Palace, he was the one key figure the queen could turn to and trust.
They married five years before she became queen, and Philip is the longest-serving royal consort in British history.
The couple had four children, eight grandchildren and 10 great-grandchildren.
"He has, quite simply, been my strength and stay all these years," Elizabeth said in a rare personal tribute to Philip, in a speech marking their 50th wedding anniversary in 1997.
The official Buckingham Palace statement was followed a few hours later by a message from the Duke and Duchess of Sussex.
Prince Harry, with his wife Meghan Markle, paid tribute to his grandfather on the website of their Archewell organisation. "In loving memory of His Royal Highness The Duke of Edinburgh, 1921-2021," the post read.
UK Prime Minister Boris Johnson paid tribute to Prince Philip in a televised address from Downing Street.
"Her Majesty said that our country owed her husband a greater debt than he would ever claim or we should ever know, and I'm sure that estimate is correct," he said.
"We mourn today with Her Majesty the Queen, we offer our condolences to her and to all her family, and we give thanks as a nation and a kingdom to the extraordinary life and work of Prince Philip, Duke of Edinburgh."
Mr Johnson said the duke lived a life of service that could be traced back to his days in the Royal Navy.
“He was the longest serving consort in history, one of the last surviving people in this country to have served in the Second World War where he was mentioned in dispatches for bravery," he said.
"From that conflict he took an ethic of service that he applied throughout the unprecedented changes of the post-war era. Like the expert carriage driver that he was, he helped steer the royal family and the monarchy so that it remains an institution indisputably vital to the balance and happiness of our national life."
World leaders pay tribute to Prince Philip
The UAE's leadership sent cables of condolences to Queen Elizabeth II on the death of Prince Philip. President Sheikh Khalifa expressed his heartfelt condolences and solace, the UAE state news agency Wam reported.
Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, and Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the UAE Armed Forces, dispatched similar cables of condolences to Queen Elizabeth.
Sheikh Mohammed bin Rashid also expressed his sympathies in a tweet describing the late Duke of Edinburgh as a close friend of the UAE.
"On behalf of people of UAE, I extend my sincere condolences to Queen Elizabeth II and the people of United Kingdom over the demise of Prince Philip, Duke of Edinburgh," the Vice President and Ruler of Dubai tweeted.
"A close friend to the UAE and other nations, he will always be remembered for his devotion to his country and people."
Sheikh Mohamed bin Zayed tweeted: “My deepest condolences to HM Queen Elizabeth II, HRH Prince Charles, the Royal Family, and the British people on the passing of HRH Prince Philip, the Duke of Edinburgh. May you be blessed with comfort and solace during these difficult times.”
The UAE Embassy in the UK paid tribute to the duke's decades of service.
"Dedicating a lifetime of service to this country, we sadly mourn his loss today," the embassy tweeted.
Tributes poured in from the United States, Europe and Commonwealth nations including Australia, New Zealand, India and Canada.
Australian Prime Minister Scott Morrison said the duke "embodied a generation that we will never see again".
"Australians send our love and deepest condolences to Her Majesty and all the royal family. The Commonwealth family joins together in sorrow and thanksgiving for the loss and life of Prince Philip. God bless from all here in Australia."
Canadian Prime Minister Justin Trudeau said the duke had helped shape his country for the better.
"A man of great purpose and conviction, who was motivated by a sense of duty to others, Prince Philip contributed so much to the social fabric of our country - and the world," he said.
Indian Prime Minister Narendra Modi said his thoughts were with the royal family.
"He had a distinguished career in the military and was at the forefront of many community service initiatives. May he rest in peace," he said.
New Zealand Prime Minister Jacinda Ardern said the duke would be "fondly remembered for the encouragement he gave to so many young New Zealanders through The Duke of Edinburgh’s Hillary Award".
European Commission President Ursula von der Leyen said: "I am saddened to hear of the passing of His Royal Highness Prince Philip. I would like to extend my sincere sympathy to Her Majesty The Queen, the Royal Family and the people of the United Kingdom on this very sad day."
Prince Philip dies aged 99 - in pictures
Condolences were also expressed by leaders in Ireland, where in 2011 the queen and Philip paid the first royal state visit for a century following generations of enmity with Britain.
Prior to this year's crisis over relations with the queen's grandson Prince Harry and his wife Meghan, the monarchy had to weather the 1997 death in a car crash of Harry's mother Princess Diana.
Tony Blair, who was prime minister then, lauded Philip "as a man of foresight, determination and courage" who was ahead of his time in the cause of environmental protection.
A formal notice of Prince Philip's death was placed on the gates of Buckingham Palace in London on Friday afternoon.
Mourners began laying flowers at both Buckingham Palace and Windsor Castle. Flags were lowered to half mast across the country and the Commonwealth.
His death comes as the world battles the Covid-19 pandemic.
England, however, is due to take a major step out of lockdown on Monday with the reopening of shops and outdoor hospitality.
A cause for celebration after months of lockdown has now turned into a period of mourning.
His death sparks a commemoration and funeral operation code-named Forth Bridge.
However, due to coronavirus restrictions there will not be a state funeral and the public were discouraged from attending commemoration events.
In line with the duke's wishes, he will lie in rest at Windsor Castle before a ceremony at St George's Chapel, the College of Arms said.
There will not be a lying-in-state ahead of the funeral.
The royal website’s usual functions have become temporarily unavailable following the announcement of the death of the Duke of Edinburgh.
The web page, www.royal.uk, instead has become a memorial page with a black background and smiling image of Philip.
The page displays the duke’s year of birth and year of death – 1921 to 2021.
A message at the bottom of the page reads: “The official website of the Royal Family is temporarily unavailable while appropriate changes are made."
Philip retired from public duties in 2017 at the age of 96.
His death came just months before his 100th birthday in June - an event typically marked in Britain with a congratulatory message from the queen, Britain's longest-serving monarch.
The couple, who celebrated their 73rd wedding anniversary in November, had been living largely in isolation at Windsor Castle, west of London, because their advanced age put them at heightened risk from Covid-19.
Philip and the queen received their first vaccinations against the virus in January.
Even before the duke's most recent stay in hospital, his longest ever, he was no stranger to health issues.
He was fitted with a stent in 2011 after suffering from a blocked artery. He had a hip operation in 2018, and in January 2019 he emerged unscathed after his vehicle was involved in a traffic accident, in which two people were injured, near the monarch's Sandringham estate in eastern England.
He gave up driving after the accident.
The prince spent four nights in hospital in December that year, receiving treatment for what was described as a "pre-existing condition".
He was discharged on Christmas Eve, in time to join the rest of the royal family for the festive period.
Since the outbreak of the coronavirus, Philip has made few public appearances.
He was last seen at a military ceremony at Windsor Castle in July, days after attending the wedding ceremony of his grand-daughter Princess Beatrice.
In November, he and the queen marked their wedding anniversary by releasing a photograph of them together at Windsor.
Philip was born on the island of Corfu with Danish and Greek royal titles.
Barely a year old, Philip was sent into exile when his uncle King Constantine was forced to abdicate by Greece’s new military government, and he departed the country with his parents and four sisters. The family initially settled in France.
Philip was formally introduced to Princess Elizabeth, the future queen, in July 1939, and they kept in touch during the war, meeting on several occasions.
The pair married in Westminster Abbey in London in 1947.
A rising star in the British navy, Philip had reached the rank of commander by the time Elizabeth ascended to the throne in 1952. He eventually shelved his personal ambitions to support his wife in the role.
Over the ensuing decades he was involved in numerous charities, including the World Wide Fund For Nature and the Duke of Edinburgh Award scheme for young people.