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

The palace stated that the 99-year-old formally titled the Duke of Edinburgh and the husband of Queen Elizabeth II, "underwent a successful procedure for a pre-existing heart condition at Saint 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.

Philip had been hospitalized since being admitted to the private King Edward VII’s Hospital in London on Feb. 16, where he was treated for an unspecified infection for nearly two weeks.

On Monday the Duke was transferred to Saint Bartholomew’s Hospital, an internationally renowned specialized cardiac care hospital also in London and home to Europe's largest specialized cardiovascular service.

The palace had pointed out that his admission was not related to COVID-19 and later said he was being treated for an undisclosed infection.

Both Philip and the Queen, who is 94 years young, received their COVID-19 vaccinations in January and chose to publicize the matter to encourage others to also take the vaccine.

Philip was able to walk into the hospital unaided when he first was admitted and arrived using private transport, rather than an ambulance, a source said at the time.

The prince 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, who turns 100 on June 10, retired in 2017 and since then he rarely appears in public. Before his hospitalization, Philip had been isolating at Windsor Castle, west of London, with the queen.

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.