Four fire engines and around 25 firefighters were at the scene of a fire at disused gas storage container in Western Road, Mitcham.
A small amount of solid residue was damaged by fire. Ten members of staff left the premises before the Brigade arrived. There were no reports of any injuries.
The Brigade's 999 Control officers took 16 calls to the blaze.
The fire created a lot smoke and people were advised to avoid the area and keep all windows and doors shut.
The Brigade was called at 0853 and the fire was under control by 1158. Fire crews from Mitcham, Wimbledon and Tooting stations were at the scene.
The fire is believed to have been accidental and caused by hot works carried out on the roof of the tank igniting solid residue below.