Fifteen fire engines and around 100 firefighters were called to a blaze at a block of flats in Barking, east London on Sunday, the fire brigade said on its Twitter feed. Six floors of the building are alight, the fire brigade said.
No injuries have been reported so far, a London Ambulance spokesman said, adding that ambulance units were still at the scene.
Footage on social media showed intense flames lapping up the front of a low-rise residential building.
Later pictures showed a less dramatic scene with flames largely extinguished.
Almost two years ago, Grenfell Tower, a high-rise social housing block in west London, was engulfed by flames in the middle of the night, killing 72 people in the country’s deadliest domestic fire since World War Two.
According to the BBC, dozens of Grenfell survivors and relatives are taking legal action in the US against three firms they blame for the fire, the BBC has been told.
The lawsuit will target the cladding maker Arconic, insulation maker Celotex and fridge supplier Whirlpool.
A successful action in the US could cost the firms involved tens of millions of dollars in damages. Two of the three firms said they would not comment on the case while official investigations into the fire continued.
Whirlpool and Arconic have both provided responses to the Victoria Derbyshire program but Celotex has not yet commented.
The first phase of the public inquiry into the disaster heard expert evidence that a small kitchen fire broke out through a uPVC window fitting and ignited material attached to the building.
The new exterior cladding and insulation was installed in 2016 as part of a £10m refit of the tower.
US lawyers representing Grenfell survivors and victims' relatives are expected to file the lawsuit this week in Philadelphia under product liability law, which is meant to hold firms responsible for injuries caused by the goods they sell.
The state of Pennsylvania was reportedly chosen as the legal jurisdiction for the suit because both Arconic, which supplied the combustible ACM panels, and Celotex, which manufactured the insulation, have their US headquarters there.
The Victoria Derbyshire program has been told a number of Grenfell residents have refused to sign up to the action, saying they believe it could become a distraction from the ongoing public inquiry and criminal investigation.
A Grenfell Tower survivor and community leader said: We respect those that wish to take action in the US, and we respect those that don't wish to.
Some experts have said there is insufficient evidence to say definitively it was to blame. A civil case for damages has to be started within two years of the fire itself because of the statute of limitations in the US.
At least two large US law firms are involved in the action.
Lawyers believe the disaster could not have taken place in the US because of tighter fire safety rules and a ban on the use of similar cladding on high-rise residential buildings.