Six fire crews were called to the blaze at Foxes Low Road at about 6.45pm on Sunday and brought the blaze under control by 9.30pm.

Firefighters were still damping down in the early hours of yesterday and the road was closed until 8am yesterday.

The roof of the factory is thought to contain asbestos but was not thought to have been a risk.

The empty building had previously been used as a bulb warehouse and a DVF hockey stick factory and children were known to play in it.

Police and fire investigators were searching through the debris yesterday for clues as to how the fire started.

A police spokesman said yesterday: "We are investigating and are treating the fire as suspicious at this stage."

Smoke from the blaze could be seen several miles away.

Mrs Lesley Gibbons, who lives 300 yards along the road from the warehouse, said: "The people across the road from it saw a glow from their upstairs window and rang emergency services. We wouldn't have known.

"My husband Clive and his father owned the building as a store years ago before it was a factory and it has been empty for at least six years now.

"We sold it years ago but don't know who owns it now. We don't think it is anyone local.

"Lots of kids have played in it and people have slept rough in it too.

"Community police were constantly coming and telling them to stay away and that it was too dangerous to play in.

"There was foam in the part of the building used as a cold store and it had an asbestos roof."