The Duke of Edinburgh, who will turn 100 in June, was taken by auto from Windsor, England, to the King Edward VII Hospital in London on February 17 for what the palace initially described as a "precautionary measure" after Philip reported feeling unwell.
Prince Philip has been moved from one hospital to another for treatment of an infection and preexisting heart condition. They will also undertake testing and observation for a pre-existing heart condition, Buckingham Palace said.
Prince Philip, who has been married to the Queen for 73 years, was admitted to the private London hospital on February 16 as a "precautionary measure" after he felt unwell, according to the palace.
Philip turns 100 on June 10 and his already lengthy stay in hospital has raised concerns because of his age, even though he was said to have been comfortable and responding to treatment.
While it provided more details on Prince Philip's health condition, the palace remained tight-lipped on the kind of infection Prince Philip is suffering from. Barts Heart Centre is Europe's largest specialised cardiovascular service, according to the hospital's website.
"The Duke is expected to remain in hospital for a few days of observation and rest".
The duke's youngest child, Prince Edward, told Sky News late last month that he had spoken with his father by phone.
"He is comfortable and responding to treatment but is not expected to leave hospital for several days".
Edward said "he's looking forward to getting out, which is the most positive thing, so we keep our fingers crossed".
Umbrellas were held up as he made his way into a waiting ambulance, at the rear of the hospital, and was taken to St Bartholomew's Hospital, also in central London.
The Duke was last seen in public in July 2020, when he briefly returned to royal duties to hand over his role as Colonel-in-Chief of The Rifles at Windsor Castle. "I think it affects all of us, and then you can only look at the clock so many times and the walls are very interesting".
Sources close to the palace had previously shared Philip's illness was not Covid related with both the Prince and the Queen receiving their first vaccines in January.