Some 200 firefighters are tackling a fire in Dagenham described by the London Fire Commissioner as the city's largest in years.
Forty fire engines have been called to the blaze, which broke out about 1:15pm at a recycling centre on Chequers Lane in Dagenham.
At the height of the incident, a plume of smoke could be seen right across London.
The London Fire Commissioner Ron Dobson said: "We've not seen a fire of this size in London for several years, it's certainly a dramatic end to the Olympics for the London Fire Brigade.
"That said though, we are still able to attend incidents across the capital and the fire cover we're providing at the Olympic venues has not been affected."
Mr Dobson said there had been no reports of any injuries caused by the blaze.
"I would like to reassure people that we are still able to attend incidents across the capital and the fire cover we're providing at the Olympic venues has not been affected," Mr Dobson said.
"At this stage we aren't sure how the blaze started as our focus is getting the flames under control. Fire crews will remain at the scene for as long as necessary and a thorough investigation will begin once the fire is out in order to establish how it started."