Worried retailers have been urged not to panic after embarrassed shopping centre bosses were taken in by a hoax chain letter warning of attacks with HIV needles.

About 70 tenants at the Castlegate Shopping Centre in Stockton, including retailers, market traders and offices, were told to be on the lookout for stray needles left on seats and in vending machines.

The managing agents for the centre, Debenham Tie Lueng (DTL), notified centre manager John Clift after receiving a copy of the chain e-mail and believed it to be true.

It claimed Staffordshire Police were investigating an incident at a cinema in Stoke-on-Trent, where a woman had sat on a chair and been jabbed by a needle with a note attached, which read: "You have been infected with the HIV virus."

The chain e-mail claimed other similar incidents had also been reported, with needles also being planted in vending machines.

As a result, Mr Clift said he followed orders from his bosses and warned retailers to put their staff on guard and urged them to regularly check public seating areas.

His circular letter to tenants said: "I would advise all tenants to use extreme caution when confronted with these types of situations and undertake regular preventative inspections of their facilities."

But yesterday, both Staffordshire and Cleveland Police said the warning was nothing more than a hoax and people had no need to worry.

A spokesman for Stoke-on-Trent Police said: "We have received no such reports and we believe the e-mail has been written to cause fear and alarm to members of the public."

Mr Clift said he accepted the e-mail was a hoax, but said centre bosses had to play safe.

He said: "We believed it was credible and so alerted our tenants with advice to pass the information on to anyone they felt necessary."

DTL Chairman Peter Preddy, who issued the warning to the Castlegate Shopping Centre, was not available for comment.