Prime Minister Theresa May said the government had arranged to test cladding on "all relevant tower blocks" .
Prime Minister Theresa May said the government had arranged to test cladding on "all relevant tower blocks" following the deadly June 14 inferno, with some failing the tests.
Meanwhile English local authorities estimate that 600 high-rise buildings have used similar cladding to the Grenfell Tower in west London.
The panels have been widely blamed for the rapid spread of the fire which consumed the 24-storey public housing block, leaving 79 people presumed dead.
Downing Street declined to specify whether the cladding on the tower block was combustible or not, citing an ongoing investigation.
"We cannot and will not ask people to live in unsafe homes," May said in a statement to parliament.
She said the relevant local authorities and fire services had been informed of those blocks failing the tests but did not specify what action would be taken.
More than 100 buildings a day can be tested and May urged landlords to send samples for rapid assessment.
All social housing landlords have been instructed to conduct fire safety checks on tower blocks.
May said landlords were expected to provide people with alternative accommodation if buildings were found to be unsafe.
"Many others living in tall residential buildings will have concerns about their safety after what happened at Grenfell," she said.
King's College Hospital told AFP that three of its patients from the disaster were given the hydrogen cyanide poisoning antidote Cyanokit as a precaution.
Manufacturer Celotex stated that the insulation in the cladding would have released "toxic gases" if it caught fire.
The National Health Service said 10 patients were still being treated in hospital, five of whom were in a critical condition.
The cladding was installed for beautification and insulation despite warnings from local residents about fire safety as part of a major refurbishment of Grenfell Tower that was completed last year.
May said "no stone will be left unturned" in a judge-led inquiry she has ordered into the blaze.
She has apologised for the chaotic official response to the fire from local and national government.
The chief executive of the local authority which owned the tower quit after fierce criticism over the council's response to the deadly inferno.
Nicholas Holgate claims he was forced out from his post in charge of Kensington and Chelsea council by the British government's Local Government Secretary Sajid Javid.
However, Javid's office denied involvement, saying it was a matter entirely for the council.
The Justice4Grenfell campaign group welcomed Holgate's departure.
May said there were now around 600 people working by the site to provide support to victims and so far there had been 500 visits to the centre.
Each family whose home was destroyed was receiving a £5,000 downpayment.
The tower itself contained 120 flats. May said 151 homes had been destroyed by the blaze and their occupants would all be guaranteed new homes on the same terms, within three weeks and as close to home as possible.
She also insisted: "Nobody is being forced to move somewhere they don't want to go."
She said the blaze would not be used as a reason to carry out immigration checks.
"All victims, irrespective of their immigration status, will be able to access the services they need," she said.
London Mayor Sadiq Khan called for an amnesty for any illegal immigrants who survived the blaze.
He told LBC radio there may have been people who were illegally sub-letting their flats and others who were illegal immigrants staying with friends and family.