He was moved to St Bartholomew's Hospital days ago.
Prince Philip has undergone a "successful procedure" on a pre-existing heart condition for which he is currently being treated in hospital, Buckingham Palace have confirmed.
In a statement, Buckingham Palace said: "The Duke of Edinburgh yesterday underwent a successful procedure for a pre-existing heart condition at St Bartholomew's Hospital.
"His Royal Highness will remain in hospital for treatment, rest and recuperation for a number of days."
He has been been in King Edward VII's Hospital in London since 16 February, a move described by Buckingham Palace as a precautionary measure with the 99-year-old feeling unwell.
