BLACKBURN town centre was thrown into chaos for more than five hours last night following a bomb threat.

The heart of the town became a no-go zone with all of pubs and clubs within 400 metres of Jubilee Street closed and motorists prevented from entering the central area.

Hundreds of Friday night revellers were evacuated from restaurants, pubs and cinemas - and bathers were rushed from Waves in foil blankets as the drama unfolded.

Police today said they were baffled why Blackburn was targeted in a phone call to the British Telecom telephone exchange in Jubilee Street just after 6.30pm.

Police immediately began evacuating pubs, restaurants and businesses and sealed off an area 100 metres around the exchange.

People were shepherded to the shopping centre as the police helicopter circled overhead broadcasting warnings about the security alert.

By 7.30pm the threat, the third of its kind in the past few weeks, was considered so serious that scores of police officers were drafted in from across the county to seal off the town centre between Great Bolton Street and Northgate.

Waves swimming pool, Mecca bingo and the Unit Four cinema complex were all evacuated as fire and ambulance crews were put on stand-by, army bomb disposal experts arrived. Searches were started although by midnight, when the alert was called off, nothing had been found.

Detective Superintendent Graham Gooch, who led the investigation, said: "It was decided, from the content of the threat and our intelligence, to evacuate the telephone exchange. We carried out searches for anything that didn't belong there, but nothing was identified."

"I really don't know why Blackburn has been targeted. The town has never been the subject of this type of threat before. We would like to take this opportunity to thank the people of Blackburn for their help and co-operation. Our main priority was to ensure public safety and we were acting on information available at the time."

He would not confirm whether the threat had been made by Irish terrorists or comment on the content of the threat.

"We would like to apologise if we have disrupted people's evening and for any inconvenience we have caused," said Mr Gooch.

In the past three weeks, the Jubilee Street area has been evacuated twice after suspect packages were found. The bomb threat came just a week after a similarly disruptive incident in Newcastle.

The police blockade brought traffic chaos. A makeshift taxi rank was set up at Bolton Road traffic lights to help stranded youngsters and revellers get home.

Buses toured the outskirts of the town because they could get nowhere near the bus station.

Cars backed up along Bolton Road and there was confusion as motorists tried to turn around with tailbacks stretching back to Lower Darwen.