Prince Philip underwent a successful heart procedure at a London hospital, Buckingham Palace said Thursday.

The palace says the 99-year-old Duke of Edinburgh, the husband of Queen Elizabeth II, "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,'' the palace said in a statement.

PRINCE PHILIP TRANSFERRED BACK TO PRIVATE HOSPITAL AS HE RECOVERS FROM HEART SURGERY, PALACE SAYS

Police officers stand outside the main entrance of St Bartholomew's Hospital where Britain's Prince Philip is being treated in London. (AP Photo/Alberto Pezzali)

Philip, 99, has been hospitalized since being admitted to King Edward VII’s Hospital in London on Feb. 16, where he was treated for an infection. He was transferred on Monday to a specialized cardiac care hospital, St. Bartholomew’s.

His illness is not believed to be related to the coronavirus. Both Philip and the monarch received COVID-19 vaccinations in January and chose to publicize the matter to encourage others to also get the vaccine.

PRINCE PHILIP TRANSFERRED TO ANOTHER HOSPITAL TO CONTINUE TREATMENT

He has had heart issues in the past. In 2011, he was rushed to a hospital by helicopter after suffering chest pains and was treated for a blocked coronary artery.

Philip retired in 2017 and rarely appears in public. Before his hospitalization, Philip had been isolating at Windsor Castle, west of London, with the queen.

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The longest-serving royal consort in British history, Philip married the then-Princess Elizabeth in 1947. He and the queen have four children, eight grandchildren and nine great-grandchildren.

The Associated Press contributed to this report.