It called the admission “a precautionary measure” taken on the advice of Philip's doctor. The palace said Philip, also known as the Duke of Edinburgh, is expected to remain for a few days of “observation and rest.”
Prime Minister Boris Johnson's office said he “sends his best wishes to the Duke of Edinburgh as he undergoes a few days of rest in hospital.”
Philip retired from public duties in 2017 and rarely appears in public. His most recent public event was a military ceremony at Buckingham Palace in July.
During England's current coronavirus lockdown, the duke has been staying at Windsor Castle, west of London, with the queen, who has performed duties such as meetings with dignitaries remotely.
Lockdown permitting, the royal household is planning celebrations, to mark Philip's 100th birthday on June 10.
Philip married the then-Princess Elizabeth in 1947 and is the longest-serving royal consort in British history. He and the queen have four children, eight grandchildren and nine great-grandchildren.
In 2011, he was rushed to a hospital by helicopter after suffering chest pains and treated for a blocked coronary artery. In 2017, he spent two nights in the King Edward VII hospital and was hospitalized for 10 days in 2018 for a hip replacement.
Philip was last hospitalized in December 2019, spending four nights in the King Edward VII Hospital for what the palace said was planned treatment of a pre-existing condition.
He was forced to give up driving at the age of 97, after smashing into a car while driving a Land Rover near Sandringham estate in January 2019. Philip needed help to get out of the Land Rover but wasn’t injured. A woman in the other vehicle suffered a broken wrist.
Even after that, Philip continued to drive a horse and carriage on private land from time to time.