"It is unclear when he will be discharged, but he is likely to remain in hospital for a few more days," said a palace statement.
Philip, 91, was taken by ambulance to Aberdeen Royal Infirmary on Wednesday while the royal couple were staying at their Scottish residence of Balmoral.
In June, Philip was hospitalized for five nights due to a bladder infection, after spending several hours on a barge during the queen's Diamond Jubilee river pageant on the Thames.//DPA