London Fire Brigade is warning people to be on the look out for cannabis factories near their homes, which can potentially start intense blazes because of the heating and lighting equipment used to grow the plants.

Fires caused by cannabis farming more than doubled in the past two years, according to new figures released by the Brigade, with one fire a fortnight last year.

Most fires broke out in residential properties, posing a risk to homes next door, and electricity is often illegally sourced, bypassing conventional routes, meaning a greater fire risk.

On May 21 2012, 20 per cent of a ground floor flat in Homerton High Street was damaged by a fire caused by a cannabis factory, while a 13th floor flat in Bethune Road, Stamford Hill, sustained damage on December 18 2010.

Cannabis farms are often booby trapped - with false floors, barbed wire and electrified door handles and windows - meaning firefighters tackling them are at greater risk of serious injury.

Signs indicative of cannabis farming include a strong, sickly sweet smell, constantly blocked off windows, strong and constant lighting day and night, as well as a constant buzz of ventilation and lots of cables.

Anyone who suspects a cannabis farm can call 101 or to remain anonymous call Crimestoppers on 0800 555 111.