Firemen, using breathing apparatus, had to cope with poisonous fumes when they tackled a fire at a Burnley polyurethane foam factory.

Police are investigating the cause of a fire in a Burnley factory which engaged 30 firemen from Burnley, Padiham and Nelson for almost four hours. The fire was at the premises of Unit 10 Ltd, upholstery and foam manufacturers, of Grenfell House, Rylands Street, near Duke Bar. Four teams of firemen, wearing breathing apparatus, fought through dense smoke to reach the centre of the outbreak - a pile of polyurethane foam, stored on the ground floor.

A spokesman for the firm told the Burnley Express yesterday that it was "work as normal" at the factory, which employs about 60 people, men and women. "The only real damage was to one fluorescent light." A sprinkler system kept the outbreak under control until firemen arrived. Other firms occupy the same building, but they were unaffected. The alarm was raised at 5.25 pm on Sunday, 1st September 1974. The fire caused slight damage to a roof, electrical fittings and 250 cubic feet of polyurethane foam.

Asked if the cause of the fire had been established, a fire brigade spokesman said: "We don't know. The circumstances are suspicious and the police are investigating." A police spokesman later confirmed this, but would offer no other comment.