Police are hunting a gang who carried out a terrifying robbery on an upmarket Chelsea jewellers, before escaping on mopeds.

The raiders, who were armed with sledgehammers, burst into a branch of Boodles in Basil Street, Chelsea just after 10.30am on Wednesday.

A video of the raid showed smoke pouring from the front of the store.

It was feared that the gang may have used smoke bombs to disorientate staff, but there were suggestions it may have been part of the store security system.