BOMB disposal experts were called in at Trowbridge on Tuesday after workmen found live Second World War ammunition on a building site.

Bythesea Road was closed for five hours, causing traffic chaos in the town, following the discovery of anti-tank and hand grenades on the McCarthy and Stone site at the former TA centre.

Army bomb disposal officer, Sgt Malcolm Quigley, said: "There were 11 items nine projector infantry anti-tank grenades and two hand grenades. They were all live."

Sgt Quigley and another bomb expert, who are based in Tidworth, detonated the arms in a series of controlled explosions, the last at just before 10pm.

The explosives were packed in sandbags supplied by the county council, which deadened the noise but it could still be heard across the town.

Sgt Quigley said: "This part of the country is littered with such items and generally nothing will ever happen to them.

"They are only dangerous when disturbed."

Police were called in as soon as the discovery was made and the site and part of the nearby county council offices were evacuated.

Emergency planning officer, John Edwards, said: "As a precaution we evacuated about 50 people, who went home a little early."

The railway line runs directly behind the site and a Railtrack emergency response officer was also called in. The explosions then had to be carefully timed to ensure that no trains were in the area.

Further investigations were carried out at the scene on Wednesday.

Inspector Steve Hedley from Trowbridge police said: "The site probably won't be searched unless there is a great deal more found, the reason being that if a bomb is buried underground, it is safer to leave it."

About 40 people work on the site and one worker, who was on site when the discovery was made, said: "As far as we were concerned the site had been cleared so it was a bit of a surprise."