The emergency at Manbat saw 150 litres of sulphuric acid spilt at its premises in the Pallion Industrial Estate.

Fire appliances attended the scene shortly after 11am yesterday as the spill spread to a neighboring property.

Workers exposed to the substance were successfully decontaminated by firefighters and taken to Sunderland Royal Hospital as a precaution.

Contact with acid vapors can cause lung damage, blisters or blindness.

A spokesman for Tyne and Wear Fire and Rescue Service, said the incident could have been very serious for the workers.

He said: "The alarm was caused by 150 litres of sulphuric acid being spilled within a battery making factory. This then permeated through to an adjacent property.

"The spillage was contained using water and soda crystals.

"A number of employees were exposed to the chemical and were decontaminated by fire service personnel.

"All casualties were conveyed to Sunderland Royal Hospital as a precautionary measure."

Manbat, a national company based in North Wales, operates as an importer, stockist and distributor of batteries for a range of equipment and vehicles, including generators, cars and medical kits.

The company took over the Pallion site in 2006 when Manbat bought out R. Thursby Ltd.

The Environment Agency, Health and Safety Executive and Emergency Planning Unit have been informed of the spill and an investigation is likely to take place.