A FIRE investigation is under way after a large factory blaze.

It took about 20 firefighters an hour to tackle the 100metre square fire at Chemviron Carbon, in London Road, Grays in the early hours of this morning.

Ten per cent of the water purifier plant was on fire as the first two fire engines, at about 5.20am and the incident commander had to call for two more crews.

Firefighters wearing breathing masks set to work using one main jet and one hose and the blaze was extinguished by 06:15am.

Two crews from Grays Fire Station and two from Orsett Fire Station attended.

A fire investigation will be carried out to establish the cause of the incident.