Firefighters were called to tackle a blaze at the Millennium Mills on the Royal Docks.
Emergency services were called just before 12.30pm after a fire broke out at the former flour mill in Mill Road.
Altogether, 58 officers and eight fire engines from Dagenham, East Ham, Plaistow, Stratford, Poplar, Shadwell, Bromley and East Greenwich were called to the scene.
It is reported that half of the fourth and fifth floors were alight and 50 builders left the building before firefighters arrived.
Three thousand new homes and up to 21,000 new jobs are due to be created at the Millennium Mills in a multi- million pound project.
The scheme was granted £12million from the Department for Communities and Local Government last month.
The site was used as a training ground for emergency services last year.
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