Buckingham Palace said Prince Philip, the 98-year-old husband of Queen Elizabeth, was taken to hospital on Friday as a precaution for treatment from a previous condition.
"The Duke of Edinburgh traveled from Norfolk this morning to the King Edwa Hospital, the seventh in London, to undergo follow-up and treatment in relation to a previous case," the palace said in a statement.
"Hospital admission is a precaution based on the advice of his doctor," the statement added.