A MAJOR mopping-up exercise was taking place last night after a series of explosions at a chemical plant in the region.

Investigations are continuing into the cause of the blaze at the Shanks chemical works on the Tofts Farm Industrial Estate, Seaton Carew, near Hartlepool, but it is believed it started when a drum of lithium waste self-heated when it came into contact with water and exploded.

This led to further explosions among other chemical drums.

A member of staff raised the alarm after spotting the fire in the storage area and the few employees on site at the time were evacuated.

It is hoped work will get back to normal once the investigation has been carried out.

A spokesman for the company said: "Our priority now is to clean the site, assess the damage and help in the investigation."

At the height of the fire, on Wednesday evening, there were 50 firefighters, 12 fire engines, one command support unit, two hydraulic platforms and a foam tender present.

The explosions could be heard for miles and residents in Seaton Carew were warned to close all doors and windows and only make necessary journeys.

George Pendlington, divisional officer for Cleveland Fire Brigade said: "We were concerned with the smoke plume heading off towards Seaton Carew and, as we did not then know what substances were involved, we decided to ask residents to close doors and windows as a precaution."

The restriction has since been lifted and Mr Pendlington said there was no danger to members of the public.

He said: "The fire is now out and a substantial mop-up operation is under way. The fire was contained on the site."

However, two firefighters were detained overnight in hospital for observation after inhaling fumes. They were discharged yesterday after being given the all-clear.

The investigation, which is expected to last a couple of days, is a joint operation between police, fire, Environment Agency and the Health and Safety Executive.

An Environment Agency spokesman said: "Officers were called to the scene of the fire to assess any environmental impact.

"Water from fighting the blaze has been directed to the on-site sewer system and is being dealt with by Northumbrian Water.

"As site regulators, The Environment Agency is now carrying out a full investigation with the help of Cleveland Fire Brigade."