Prince Philip has undergone a "procedure" relating to his pre-existing heart condition, Buckingham Palace have confirmed.

The 99-year-old was admitted to hospital more than two weeks ago with an infection and was moved to St Bartholomew's in London earlier this week for further treatment.

In a statement, the Palace said that the Duke of Edinburgh is now 'recuperating' after an unspecified operation but did provide any further information.

"The Duke of Edinburgh yesterday underwent a successful procedure for a pre-existing heart condition at St Bartholomew's Hospital," the statement said.

"His Royal Highness will remain in hospital for treatment, rest and recuperation for a number of days."

The news of Philip's operation comes just days before the broadcast of a highly-publicised TV interview with his grandson Prince Harry and Meghan Markle.