The tragic blaze at Grenfell Tower was started by a Hotpoint fridge freezer, the Metropolitan Police confirmed this morning.
The police are also considering manslaughter charges following the fire; seventy-nine people are confirmed dead, missing, or presumed dead after the blaze ripped through 150 flats in the Kensington building.
Detective chief superintendent Fiona McCormack said in a statement that the building's insulation and cladding, installed as part of a £10m refurbishment of the block, also failed fire safety tests.
Every company involved in the refurbishment of the building is being investigated.
The authorities will not check the immigration status of anyone affected by the fire, McCormack added.
The tower is still being searched by the emergency services, with officers working under "difficult and distressing" circumstances, she said. The operation is so complicated it could take until the end of the year.
The Department of Business Energy and Industrial Strategy is working with Hotpoint on the safety of the fridge, and further tests are being carried out on the appliance.
Whirlpool, which makes Hotpoint and Indesit products, told consumers in February to unplug potentially dangerous tumble dryers due to fire risk.
Last year, an investigation by the London fire brigade found that a faulty Indesit tumble dryer was responsible for a fire in an 18-storey block in Shepherd's Bush.
Whirlpool said in a statement: “Words cannot express our sorrow at this terrible tragedy. We offer our most profound condolences to the victims, those who have lost loved-ones, homes, and possessions, and to their friends and families.
“We are working with the authorities to obtain access to the appliance so that we can assist with the ongoing investigations."