Ten fire engines and around 70 firefighters are tackling the fire in a high-rise building on Biscayne Avenue in Blackwall, after they were called at 1.28 p.m. (1230GMT), the London Fire Brigade (LFB) said in a statement, according to Anadolu Agency.
Half of a flat and balcony on the 25th floor of the building is alight while the fire is producing a large amount of smoke, said the LFB, urging locals to keep windows and doors closed and avoid Biscayne Avenue.
"The cause of the fire is not known at this time," it added.
Earlier in the day, 200 firefighters responded to another fire at a high-rise tower block partly used by residents in Dagenham, East London.
MNA