Investigators will consider bringing manslaughter charges over the Grenfell Tower 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.
Metropolitan Police said manslaughter, health and safety, and fire safety charges will be considered.
Experts have now concluded the fire had started in a fridge freezer. Police said the blaze had not been started deliberately.
Asked if the insulation and aluminium tiles used were acceptable for such buildings, Detective Superintendent Fiona McCormack told reporters: "No they're not."
Ms McCormack said the tests carried out were "small scale" but added: "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. Ms 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 that was involved in the Grenfell fire. The model was manufactured between 2006 and 2009.
Whirlpool owns the Hotpoint brand in the Europe and Asia Pacific regions. In the United States, the Hotpoint brand now belongs to Haier, following the Chinese group's purchase of General Electric Co's appliance business.
The government said it was urgently conducting tests on some 600 high-rise buildings in England which have exterior cladding, often added to insulate them or improve the external appearance of ageing blocks. Some councils have begun removing the panels.
Problems have so far been identified in 14 buildings in London, Manchester and elsewhere in England, it added.
In Salford, cladding is to be removed from nine of its residential tower blocks because of safety concerns. "Government tests are under way but is already clear the cladding on our blocks must be removed, the city's mayor, Paul Dennett, said. " There will be no waiting around... while there are any questions about the safety of our residents."
Nine of those who died on 14 June have been formally identified so far. Nine people remain in hospital, with three people still in critical care.
Ms McCormack said forensic search may not be complete until the end of the year. "There is a terrible reality that we may not find or identify everyone who died due to the intense heat."