Investigators said on Friday they would consider bringing manslaughter charges over the London tower block fire that killed at least 79 people.
The outside cladding engulfed by the blaze has since been shown to fail all safety tests, police said. They have already seized material from a number of undisclosed organizations.
Detective Superintendent Fiona McCormack also said experts had now concluded the fire, the mostly deadly blaze in London since World War Two, had started in a fridge freezer.
The blaze has provoked anger and heaped pressure on Prime Minister Theresa May, who is fighting for her political survival after her party lost its parliamentary majority in a snap election at a time when Britain is beginning divorce talks with the European Union.
The speed at which the fire engulfed the 24-storey Grenfell Tower raised questions about the external cladding on the block.
Asked if the insulation and aluminium tiles used were acceptable for such buildings, McCormack told reporters: “No they’re not.”
“All I can say at the moment is they don’t pass any of the safety tests. So that will form part of what is a manslaughter investigation.”
As well as possible manslaughter, police will consider health and safety offences and breaches of other building regulations. McCormack said all companies involved in the building and refurbishment of the building would be reviewed.
Britain also ordered an immediate technical examination of the Hotpoint fridge model FF175BP, which had not been subject to any recall to establish whether further action should be taken, but said there was no need for owners to switch off their appliances.