'Apocalyptic' fire engulfs block of flats in London's north-west

A fire has taken hold of at least four balconies at a block of flats in north-west London, sending large flames and plumes of smoke into the sky.

More than 50 firefighters were called to tackle the raging blaze on Heritage Lane in West Hampstead shortly before 11.30am (8.30pm AEST).

The blaze spread from three to four balconies as crews tried to stop the flames, which was brought under control at 1.10pm (10.10pm AEST).

Footage posted to social media showed the building engulfed by a plume of black smoke.

Witness Kirsten Levermore told the BBC it looked “apocalyptic” and “like a bomb had hit it”.

There were no reported injuries and the building’s developer said they were in “close communication with all affected residents.”

“Our primary task in the coming hours is to ensure their security and to organise temporary accommodation.”

It’s not known what caused the fire.