The fire started just after 1900 GMT on Wednesday with reports of two explosions, and it took hold again at 0200 GMT on Thursday.

People living near Shanks Chemical Processing, Seaton Carew, were warned to stay inside and close windows.

An investigation is taking place into the cause of the fire, which was brought under control on Thursday.

Breathing difficulties

At its height, there were 12 fire crews along with special units and the police forward command unit at the scene.

Two firemen were taken to hospital after complaining of breathing difficulties.

A clean-up operation followed during which the fire brigade was on standby.

Excess water was also removed from the site in case it may be contaminated.

The fire brigade said there was no danger to the public.