LONDON, ENGLAND (BNO NEWS) -- Queen Elizabeth II's husband Prince Philip walked out of a private hospital in the British capital of London on Monday, looking well and waving to onlookers after spending 11 nights in hospital while recovering from exploratory surgery on his abdomen.

The 92-year-old prince walked into London Clinic on June 6 after attending a garden party at Buckingham Palace just hours earlier. He underwent exploratory surgery on June 7 following abdominal investigations, and the results were analyzed last week as he continued to recover.

The Duke of Edinburgh looked extraordinarily fit as he left the hospital, thanking staff members and waving to onlookers. "The Duke is in good condition and good spirits," Buckingham Palace said in a brief statement. "The Duke has expressed his thanks and appreciation to medical staff at the London Clinic and the many members of the public who have sent good wishes."

Monday's release from hospital was several days earlier than expected, as the royal palace had initially said he would remain at London Clinic for up to two weeks. But he will now take a period of convalescence, which Buckingham Palace has said will last approximately two months.

Prince Philip was forced to spend his 92nd birthday at London Clinic, but was visited by both Queen Elizabeth II and Prince Edward, the couple's youngest child. The celebration was marked by a 41-round royal salute in London's Green Park and a 62-round salute at the Tower of London, as well as a 'Happy Birthday' song being played during Changing of the Guard at Buckingham Palace.

The queen's husband is known to be active and robust for his age, although he suffered several minor health scares in recent years.

The prince was hospitalized in June 2012 after developing a bladder infection, just a day after accompanying his wife on a royal barge that formed part of a River Thames flotilla to mark the Queen's diamond jubilee. It followed a hospitalization in December 2011, during which Prince Philip was found to have a blocked coronary artery and he underwent a 'minimally invasive' procedure of coronary stenting.

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