HUNDREDS of pigs died yesterday after a blaze severely damaged a farm building near Darlington.

It is not yet known exactly how many pigs died, but it is estimated that it was more than 300.

The alarm was raised at 6.22am yesterday with reports of a barn fire at Raby Farm in Sadberge, near Darlington.

Four fire engines were sent to the scene and the fire crews battled for nearly fours to extinguish the blaze in the single-storey steel barn, which also contained hay, machinery and fertiliser.

But, by the time the fire had been put out, the vast majority of the pigs had died. The animals were due to be moved out of the building on Friday.

Fire inspectors were last night working at the scene to determine the cause of the fire. It is suspected that an electrical fault on a tractor in the building could have started the blaze.

The family, who live and work on the farm, have spoken of their devastation following the incident.

Sally Shepherd, whose husband runs Raby Farm, said: "My husband is distressed about this. In fact, we are all extremely upset about it. If it had been next weekend the pigs wouldn't have even been there."

The fire crews were hindered by the presence of significant amounts of nitrogen-based fertiliser in the barn.

They had to use defensive methods of firefighting to minimise the risk.

John Walkden, watch manager at Durham and Darlington Fire and Rescue Service, said: "The barn was severely damaged and we did have concerns about the fertiliser. When you put water on fertiliser it can cause it to explode."

"It was a fairly delicate operation. We had to keep the water away from the fertiliser, but keep the fire under control at the same time. Fortunately, the fertiliser wasn't on fire when we arrived."

The Department for Environment, Food and Rural Affairs have been informed about the fire, and will carry out their own investigation.

Structural engineers will examine the barn, which measures 90 metres by 20 metres, to decide whether it can be repaired.