A build-up of grease and oil in the extraction system is believed to be the cause of fire at a kebab shop on Epsom Road in Morden.
A shop worker raised the alarm when they say a flame coming from the extractor hood above the charcoal grill.
The extraction system from the ground to the second floor was destroyed by the blaze. Part of the ground floor was also damaged by fire. There were no reports of any injuries.
London Fire Brigade spokesperson said:
"We'd like to remind restaurant and takeaway owners to ensure they don't have dirty ducting. If you don't clean the ducting in your extraction system regularly, you're at a greater risk of ducting fires.
"You should also make sure you keep the hob, cooker hood and extractor fan clean too – built up fat and grease can ignite and cause a fire."
Firefighters' top tips for restaurants and takeaways:
The Brigade was called at 1948 and the fire was under control by 2202. Six fire engines and around 40 firefighters from Sutton, Mitcham, Wimbledon, Croydon and New Malden fire stations.