Prince Philip is "progressing satisfactorily" after his exploratory operation.
The Duke of Edinburgh - who turns 92 next week - is expected to spend up to two weeks at the London Clinic where he underwent the procedure on Friday (07.06.13) "following abdominal investigations".
A statement from Buckingham Palace said: "At this early stage, he is progressing satisfactorily."
Royal commentator Richard Fitzwilliams says the prince is a "most impatient patient" who loves to keep busy.
He told CTV's 'Canada AM': "There's no question that he is somebody with an absolutely iron constitution. One of the issues with the duke is it's very difficult to get him to slow down. He'll be a most impatient patient.
"Nobody wants to cause concern unnecessarily, because he's a much-loved member of the family.
"So it's a question of balance. You don't want to cause concern, but equally you want to keep your concerned public informed."
Last August, the duke spent five nights at Aberdeen Royal Infirmary, Scotland, receiving treatment following the recurrence of a bladder infection.
But following his release from hospital he refused to cut back his schedule and returned to work shortly afterwards.
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