LONDON, March 1 (Reuters) -- Britain's Prince Philip, the 99-year-old husband of Queen Elizabeth, was transferred to a different hospital in central London on Monday to have tests for a pre-existing heart condition as well as receive treatment for an infection.

Philip, the Duke of Edinburgh, was admitted to London's private King Edward VII hospital two weeks ago for treatment for an unspecified infection that is not related to COVID-19.

On Monday, Buckingham Palace said he was moved to St Bartholomew's Hospital, which is a center of excellence for cardiac care, for further treatment and observation.

"The Duke remains comfortable and is responding to treatment but is expected to remain in hospital until at least the end of the week," the palace said in a statement.

Photographers and TV crews at the King Edward hospital had earlier seen a patient being moved into an ambulance, shielded from watching media outside by staff with umbrellas and police, although there was no confirmation this was the prince.

The 94-year-old monarch has remained at her Windsor Castle home to the west of London, where the couple have been staying during the coronavirus lockdown, and last week continued to carry out her official duties, albeit by video.

They have both received their first dose of the COVID vaccine, and the Duke's illness is not related to the virus.

Philip has required hospital treatment a number of times in the last decade for a recurrence of a bladder infection and at Christmas in 2011 he had an operation to clear a blocked artery in his heart after being rushed to hospital suffering with chest pains.