AN investigation is continuing into the cause of a fire in an office building that needed more than 20 firefighters to bring it under control.

Police are treating the blaze at Total Recycling Services, in Lingfield Way, Darlington, as suspicious.

The two-storey office block at the business was well alight when emergency services arrived late on Saturday.

It is understood the building was empty at the time of the incident, with no one hurt.

Firefighters were called at 11.20pm and remained on the scene until shortly after 4am.

Windows had been smashed by the force of the blaze, while the back corner of the office building – Innovation House, in Lingfield Way – had suffered structural damage.

Fire crews, including units from Darlington, Newton Aycliffe, Sedgefield and Bishop Auckland, had to battle to contain the blaze to the building, as there are dozens of bales of paper in the yard.

The blaze is the latest blow for the recycling company, after more than £50,000-worth of equipment was stolen in a burglary last month.

John Robson, group manager for County Durham and Darlington Fire and Rescue Service, was one of the officers at the scene.

He said “There was substantial damage to the building.

“Our main objective was to make sure the building was safe to enter in order to extinguish the fire.”

Mr Robson said firefighters were confronted with a number of fires as they tried to bring the incident under control.

He said it was not clear whether this was because the fire had spread as it grew, or because there was more than one source of fire.

“The investigation will hopefully bring that matter to light – we are keeping an open mind,” he said.

Mr Robson praised firefighters for their approach to tackling the blaze.

He said: “I had to travel from Durham City to the incident and, by the time I arrived, crews had put together a good plan and had it under control within 60 minutes.”

No one from Total Recycling Services was available for comment.

Police are appealing for anyone who was in the area between 10pm and midnight on Saturday to call officers on 101.