A woman was treated on scene for smoke inhalation as 40 firefighters dealt with a fire at a tower block in Bow.
Six fire engines were called to the block of flats on Daling Way, off Old Ford Road, at 4.10pm on Wednesday, June 29.
Part of a flat on the ninth floor of the 20-storey building was damaged by the fire, which was declared under control by 4.43pm.
A London Fire Brigade spokesperson said: "Investigators believe the blaze was accidental and caused by the unsafe disposal of smoking materials."
The brigade's 999 control officers received eight calls to the blaze.
Crews from the Bethnal Green, Homerton, Poplar, Shadwell, Shoreditch and Millwall fire stations were at the scene.
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