Prince Philip has been admitted to hospital in London for a planned hip operation, Buckingham Palace said.
The Duke of Edinburgh, 96, is set to undergo hip surgery at the King Edward VII Hospital on Wednesday.
Buckingham Palace said he was admitted to the hospital on Tuesday and that further updates would be issued when appropriate.
A statement from Buckingham Palace said: “His Royal Highness The Duke of Edinburgh was admitted to King Edward VII Hospital in London this afternoon, for planned surgery on his hip which will take place tomorrow.
“Further updates will be issued when appropriate.”
Philip is said to have complained of a problem with his hip which caused him to miss a Windsor Castle event with the Queen last week.
At the time the Queen’s consort was said to be experiencing some trouble with the joint.
The Queen had marked Easter Sunday without Prince Philip at this years’ service. He was absent from the Easter Mattins Service at St George’s Chapel where Meghan Markle and Prince Harry will wed in May.
He also missed last Thursday’s Royal Maundy Service.
And earlier last month the duke did not attend an event with the Duke of York and Queen because he was reportedly “under the weather”.
But the Duke has generally been of good health throughout his life and has kept active well into his later years and is thought to be keeping busy now he has effectively retired from royal duties.
Scarlett McNally, an orthopaedic surgeon and council member of the Royal College of Surgeons, said: “Any operation and any anaesthetic carries some risk.
“What is most important is someone’s fitness, as in their heart and lung fitness, how much exercise they do and how well nourished they are. That’s more important than someone’s chronological age.”
The duke stepped down from his public duties last summer but on occasion does attend events with the Queen.
When it was announced last year that he would be retiring from official engagements, Buckingham Palace stressed that the decision was not health-related and he had the full support of the Queen.
King Edward VII is the private hospital of choice for the royal family and has been treating members of the monarchy for decades.
It was founded in 1899 at the suggestion of the then-Prince of Wales, and has treated most senior members of the royal family, including the Queen, Prince of Wales and the Duke of Cambridge.