Firefighters are urging people to ensure cigarettes are fully extinguished after a flat fire on Marsh Drive in Colindale.
A third floor flat and its balcony was damaged by fire after a discarded cigarette ignited items on a shared balcony. The alarm was raised after a security guard saw smoke and flames coming from the balcony..
The reminder to properly extinguish cigarettes before discarding them comes on No Smoking Day.
A London Fire Brigade spokesperson said: "We’d rather you didn’t smoke at all but if you do, it’s absolutely vital you ensure your cigarette is completely out when you’ve finished smoking it.
"If you don’t, you risk causing a fire which could not only destroy buildings, but also cost you your life."
The Brigade was called at 1006 and the fire was under control at 1105. Four fire engines and around 25 firefighters from West Hampstead and Hendon fire stations attended the scene.