LONDON - Britain's Prince Philip was taken to a London hospital on Thursday for a planned operation on his abdomen, Buckingham Palace said, in the latest round of medical treatment for Queen Elizabeth's 91-year-old husband.

The British monarch's consort of more than 65 years, who turns 92 on Monday, is expected to spend two weeks at the London Clinic after undergoing "an exploratory operation following abdominal investigations", the palace said in a statement.

A palace spokesman said the prince's admission had been planned and was not an emergency. He was driven to hospital in his own car and walked into the building.

Earlier in the day, the prince, who also has the title of the Duke of Edinburgh, attended a garden party at Buckingham Palace with his 87-year-old wife. Television footage showed him in a grey top hat and tails, smiling as he chatted to guests.

Royal aides said there would be regular updates on his condition but asked media to refrain from speculating about the operation and the length of stay in hospital.

Philip has needed hospital treatment four times since Christmas 2011, including for a bladder infection during the queen's Diamond Jubilee a year ago, which took some of the gloss off nationwide celebrations for the generally popular monarch.

He spent Christmas 2011 in hospital where he underwent an operation to clear a blocked heart artery after suffering chest pains.

The longest-serving consort in British history has won admirers for his charity work and his steadfast support of his wife, but is also prone to make verbal gaffes in public.

"My best wishes to the Duke of Edinburgh who is in hospital tonight. I hope he has a swift recovery," Prime Minister David Cameron said on Twitter.

The queen needed hospital treatment in March for gastroenteritis. In May, Buckingham Palace announced she would not attend the Commonwealth Heads of Government Meeting later this year in Sri Lanka, the first such gathering she has missed for four decades, as part of a review of her long-haul travel.

Son of the exiled Prince Andrew of Greece, Philip married Princess Elizabeth in 1947.  

They met when she was 13 and visited the naval college where he was a cadet, and following World War Two they became engaged.