AN arson investigation was launched today after a blaze gutted a former Worcester business.

The city's Tybridge Street was closed for two hours as firecrews fought the blaze at Booker's Cash and Carry.

Firefighters used a turntable ladder to tackle the fire, which is believed to have broken out in the stairwell of the Grade II Listed building just after 4am.

At its height, flames could be seen leaping from the roof of the two-storey Georgian red-brick building from the city's main river bridge.

Up to 20 members of Green Watch spent more than an hour bringing the fire under control.

Worcester police were also called to the incident, which they confirmed today was being treated as arson.

"The roof has collapsed on to the first floor," said Station Officer John Das Gupta, speaking at the scene.

"The ground floor is unaffected by the fire and heat. Externally the structure is safe, but internally we're concerned about its stability."

He said firefighters had to systematically work their way through the building, checking for "pockets of fire" below roof slates, which had tumbled on to the first floor.

They also carried out a sweep for any people being in the derelict building, but found no evidence of anyone trapped.

Police diverted traffic through St John's and down Henwick Road while Tybridge Street - the main artery from the Westside of Worcester to the city centre - was closed. Two lanes of the three-lane road were reopened just before 7am, and it was completely re-opened by 9am when crews left the scene.

Hereford and Worcester Fire Brigade has been called to a number of fires at the building and adjoining premises since Booker moved its operations in July, 2000, to a new store at the Shire Business Park, Warndon.

The most blaze recent was in March this year when waste paper was set alight.

Worcester City Council said plans to redevelop the site had been submitted by a Manchester-based architecture firm. The Georgian building - formerly Booker's offices - would be converted into retail premises.

Homebase has also applied to the council to extend its Tybridge Street premises.