Four fire engines and around 25 firefighters attended a fire in the basement of an office building on Great Portland Street in Westminster.
The fire, which was discovered after the automatic fire detection system activated, destroyed the storeroom within the basement. The cause of the fire is thought to be due to the unsafe disposal of cigarettes being thrown into the ventilation holes in the pavement, which caught fire to combustible materials in the storeroom below.
A London Fire Brigade spokesperson said: "While it is safer to smoke outside people need to make sure cigarettes are put out and disposed of properly. Our crews have had to attend numerous fires caused by cigarettes that have been carelessly discarded."
The Brigade were called at 1919 and the fire was under control at 2017, crews from Soho and Paddington attended the scene.