The Duke of Edinburgh, the 90-year-old husband of Britain's Queen Elizabeth II, underwent successful heart surgery on Friday for a blocked coronary artery, Buckingham Palace said.
The duke underwent an "invasive procedure of coronary stenting" after being taken to hospital with chest pains, the palace confirmed.
"Following tests at Papworth Cardiothoracic Hospital in Cambridge this evening the Duke of Edinburgh was found to have a blocked coronary artery which caused his chest pain," the palace said in a short statement.
"This was treated successfully by the minimally invasive procedure of coronary stenting. Prince Philip will remain in hospital under observation for a short period."
The duke, also known as Prince Philip, was taken by helicopter to Papworth Hospital in south east England from Sandringham House, where the family was enjoying a Christmas celebration, British media reported.