Firefighters sealed off Coleford's Ribena factory yesterday after an early morning chemical spill.

Crews from across Gloucestershire raced to the GlaxoSmithKline factory when a fork lift truck driver pierced a chemical drum.

Around 30 firefighters, including the environmental unit, were at the plant for around four hours while the clean-up operation took place.

Staff arriving for a day shift at the factory, which employs around 500 people, were turned back at the gates by police and fire crews.

The area around the spill was evacuated, but most of those already working on the site were allowed to carry on.

An 800-litre drum containing Mezzo Divosan, a chemical used for the sanitation of drums and fillers and other equipment in the food industry, was spilt.

No one was injured, but firefighters wore protective clothing and breathing apparatus to hose down the area.

Michael Allen, from Glaxo- SmithKline, said the chemical would have been neutralised very quickly and everything was back to normal by 9.45am.

He said: "There were no casualties and the fire crews and environmental unit responded fantastically. The area was sealed off as a precautionary measure as safety is paramount in these situations.

"But the emergency services and our staff contained the spill very quickly and, as far as I know, there has been no lasting damage to the environment at all."

A fire service spokesman said the department was called out at 5.15am after a container containing 800 litres of a mixture of chemicals, including nitric acid, was accidentally punctured.

He said: "The contents had emptied down the internal roadway into the surface water drains. We evacuated the immediate area and secured the factory until we could confirm our emergency action plan.

"The Environment Agency was also in attendance and after some four hours we hosed down the area with large quantities of water and made safe."

Firefighters from the Forest were joined by the environmental protection unit from Stroud station.

A spokesman for the Environment Agency said staff arrived at 7am and set up an incident room to investigate the spill.

A spokesman said: "We are currently awaiting a report from the site regarding the cause of the incident."