Guard dogs on the Westfield site will be muzzled after claims that a woman was bitten during a patrol.

A source has claimed a cleaner was bitten by a guard dog on patrol with a dog handler at around 4am on Thursday at the Westfield shopping centre, Shepherd's Bush - which is due to open tomorrow.

A spokesman for Omni, the security company which patrols the site, said: "A lady working at the site was apparently bitten on her hand by a guard dog belonging to, and under the control of, Omni Security.

"Although it appears that the dog did not break any skin and the lady declined any first aid, the dog and handler have been removed from further duties until both have been re-assessed.

"As a further precaution, we have instructed our handlers that all dogs working on this assignment should be muzzled, although this is not normal practice within the security industry."

Omni denied the source's claims that the dog, called Merve, had been trained to bite and that both handler and animal were inexperienced.

The spokesman added: "We work under their strict rules of conduct and have an unblemished safety record with its dog unit. The public can rest assured that the incident is being thoroughly investigated and appropriate action will be taken if necessary."