London: The Duke of Edinburgh was last night treated for a blocked coronary artery and a successful "invasive procedure of coronary stenting" was performed, Buckingham Palace said.
A Buckingham Palace spokesman earlier said he was undergoing "precautionary tests" at Papworth Hospital in Cambridge.
Prince Philip, 90, was taken to hospital from Sandringham, in Norfolk, where the royal family traditionally spends its Christmas break.
He was reported to be taken in a helicopter to Papworth, which is the UK`s largest specialist cardiothoracic hospital.
Prince Philip is the longest-serving royal consort and celebrated 64 years of marriage in November.
Former press secretary to Queen Elizabeth, Dickie Aribiter, told BBC: "He has had these chest pains before and I don`t think it`s anything untoward, but given his age they are being safe rather than sorry. I am sure we are going to see him on Christmas Day and he can look forward to accompanying the Queen in the new year."