A ram-raid at Oxford's Clarendon Centre was not reported until ten minutes after the attack took place, police said.

Three men in a stolen dark green Austin Maestro drove through a plate-glass door at the back of the centre, which is under constant CCTV surveillance.

After driving through the L-shaped arcade, they smashed into Ernest Jones' jewellers and grabbed designer watches worth thousands of pounds.

The raid happened at about 4am on Saturday. By the time police arrived at the scene, the thieves had vanished.

Security camera film was being studied by detectives.

Police today appealed for information. They also want to hear from anyone who recognises the description of the car, or who finds it abandoned.

Security managers at the centre were not available for comment. The Ernest Jones shop was closed on Saturday.

Insp Malcolm Haddock, of Oxford police, said: "We responded as soon as we got the information, which was at 4.11am, saying the incident had happened ten minutes ago."

"Security said they had CCTV footage, and police units were sent straight away, arriving within three minutes."

He was unable to say why the call reached the police so long after the raid took place.

Fiona Lill, manager of the Vodafone outlet at the centre, said she and her staff had been shaken by the raid.

"When we turned up this morning it made us feel sick," she said.

Alain Chong, manager at the Dixon's store, said they had never had any worries about security at the centre.