THE cause of a fire that burned for more than two days on an industrial estate may never be known, experts said yesterday.

Crowds of people turned out to watch as 70ft flames leapt into the air when the fire started at Justwood, on the Alliance Industrial Estate, in Albert Hill, Darlington, on Monday night.

It is estimated about 500 tonnes of rubbish and wood, due for recycling, were destroyed by the blaze.

Manager of Justwood, Tony Shepherd, said he suspected that children messing around on the industrial estate had started the fire.

Yesterday, Jack Elliott, of Darlington fire station, said there was very little chance that the investigation team would be able to determine the cause of the blaze.

"Our investigators should be able to look at the site in the morning, but I wouldn't be too hopeful because there isn't a lot left to investigate," he said.

"It could be spontaneous combustion, it could be kids. The extent of the devastation makes it hard to find out exactly what started it. It is made even harder because we have flattened the piles as we tried to put the fire out."

He said that since the fire started on Monday evening, more than 50 firefighters had been involved in manning the site as they waited for the fire to burn itself out.

"We have really made inroads and worked really hard. If it is not completely out by midnight (last night), I will be surprised.

"We have got rid of the majority of the wood and rubbish," he said.

Neither the police nor the fire service are investigating any suspicious circumstances as yet.