Smoke was seen pouring out of the top of Barclays Global Headquarters at One Churchill Place in Canary Wharf, east London, Daily Star reported.

Fire engines were heard screeching towards the 156m high skyscraper, which has 33 floors.

In a statement, London Fire Brigade said: "Around 60 firefighters have been called to an air conditioning unit which is alight on the top of a 33 storey tower block in the Canary Wharf area."

The blaze broke out at around 12.39am Saturday morning.