The Duke of Edinburgh has undergone a successful procedure for a pre-existing heart condition, Buckingham Palace has said.
The palace said the duke would remain in hospital for treatment, rest and recuperation for a number of days, reports the BBC.
Prince Philip, 99, has already spent 16 nights in hospital.
He was being treated for an infection and moved to St Bartholomew's Hospital in London on Monday for tests and observation on his heart condition.
Buckingham Palace said the procedure took place on Wednesday.In 2011, Prince Philip was taken to hospital by helicopter from Sandringham after suffering chest pains as the royal family was preparing for Christmas.
He was treated for a blocked coronary artery at Papworth Hospital in Cambridgeshire and had a stent fitted.
The duke, who turns 100 in June, travelled by car from Windsor to King Edward VII's hospital in Marylebone, central London, on 16 February as a precaution after feeling unwell.
The exact reason for his initial admission was not disclosed, but it was not related to coronavirus.
On Monday, Buckingham Palace announced he had been transferred to Barts by ambulance.
St Bartholomew's Hospital in the City of London is an NHS hospital and home to Europe's largest specialised cardiovascular unit.