The blaze was on the western edge of the Olympic Park in Waterden Road, Hackney Wick, near Stratford, east London, on the site of an empty warehouse, which was in the process of being demolished.

Early indications were that nobody was hurt in the incident and police said there was no explosion.

Fifteen fire engines and 75 firefighters were sent to the scene.

David Higgins, chief executive of the Olympic Delivery Authority, said: "There will be a full investigation into this fire in a disused warehouse which was being prepared for demolition. Initial indications would suggest that this was an accident rather than arson.

"We are in touch with local residents and are keeping them informed of the situation.

"There has been a first-class response from the emergency services. Meanwhile, work is continuing in the rest of the park."

Currently 20 traveller families live at Waterden Crescent off Waterden Road. They are due to be moved as their site is in the Olympic Park.

A spokesman for the London Development Agency (LDA), which is responsible for helping the travellers relocate, said the site is around a quarter of a mile from the blaze. He said: "As soon as we heard the first thing we thought about was the travellers and we got in touch with their landlord, Hackney Homes, and they had someone on site immediately."

He said he understood that the blaze was in an empty warehouse that could have been shared by a few businesses before they had to relocate to make way for the Olympic Park.