AceShowbiz - The Duke of Edinburgh has been transferred to another London hospital by ambulance where he will undergo tests for an pre-existing heart condition, Buckingham Palace has announced.

The husband of Britain's Queen Elizabeth, was taken from King Edward VII's Hospital to St Bartholomew's Hospital at 11.15 am on Monday, March 1 morning. Buckingham Palace said in a statement doctors would continue to treat the 99-year-old for an infection but would also "undertake testing and observation for a pre-existing heart condition", reported Britain's The Daily Telegraph.

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

In 2011, the Duke received treatment for a blocked coronary artery after suffering chest pains. A "minimally invasive procedure of coronary stenting" was performed.

In pictures obtained by the publication the Duke was carefully shielded as he left the private King Edward VII hospital in Central London. Large umbrellas were used as a protective screen as he was transferred into a waiting ambulance.

According to St Bartholomew's website, it is "an internationally renowned hospital in the City of London, close to St Paul's cathedral. It is a centre of excellence for both cardiac and cancer care".

BBC Health correspondent Hugh Pym said that while the nature of the Duke's pre-existing heart condition remains to be seen, he speculated that it might be related to the stent operation in 2011 or that the infection had somehow exacerbated an existing heart condition.

"Certainly he will be monitored extensively, with some of the best specialists in the country at Barts heart centre," he said. "But I think, probably, it's more than just monitoring. I think he has gone to this specialist centre because of the possibility - no more than that - that the doctors feel there may be a need for an intervention or procedure to be carried out."