Cladding on 34 tower blocks in 17 council areas in England has failed fire safety tests, the government says.
The results mean every sample has failed the tests so far. The government plans to test up to 600 blocks.
The updated figures came as Camden became the first authority to evacuate residents over concerns, asking those living in four buildings to leave.
The council said it had no option but to move residents of 650 flats on the Chalcots estate while work takes place.
Communities Secretary Sajid Javid said the residents had shown "calm and stoicism".
But he said cladding itself is not dangerous and a test failure does not necessarily mean a building will have to be evacuated.
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Camden's decision to evacuate was because the failed testing of external cladding was "compounded by multiple other fire safety failures", said Mr Javid.
The testing of potentially combustible cladding "is running around the clock" and interim safety measures are being put in place for all affected buildings, he added.
The Department for Communities and Local Government (DCLG) pointed out that local authorities have been asked to prioritise buildings they had most concern over.
The DCLG's testing programme, which began on Wednesday, is able to test 100 samples a day. If needed, further lab capability could be provided.
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Fire crews have been put on watch at the Chalcots estate
Prime Minister Theresa May said "necessary" steps will be taken to find people evacuated from the Chalcots Estate.
Mrs May said: "We are making sure that the authority has the ability to do what is necessary to ensure people have somewhere to stay and that the work is done so that those tower blocks will become safe for them to return to in future."
The Local Government Association said some councils have introduced 24-hour a day warden patrols, to mitigate the risk before cladding is removed.
"Anyone living in a high-rise building can be reassured that their council will act on any advice from the fire service to ensure their safety," a spokesman said.
Other high-rise buildings, such as some used by the NHS, are also being tested.
The DCLG have named seven of the 17 local authorities where high-rise buildings have failed fire safety tests. They are:
Camden - where residents have been evacuated from four blocks on the Chalcots estate
Brent - where a housing association tower block, Elizabeth House, has cladding but London Fire Brigade advises it is not a risk
Barnet - where cladding put up on three towers in Granville Road, NW2, in 2012 is to be removed as precautionary measure
Hounslow - where Clements Court tower in Cranford is to have outer cladding removed
Manchester - where 78 panels are being removed from one area of the Village 135 development in Wythenshawe
Plymouth - where three blocks on the Mount Wise Tower estate were found to have cladding made from similar material to Grenfell Tower
Portsmouth - where the city council is removing cladding from Horatia House and Leamington House in Somerstown
Earlier, Camden council's Labour leader, Georgia Gould, said the authority had acted "as swiftly as we possibly can" to ensure people's safety.
Ms Gould said the fire service "told us they could not guarantee our residents' safety in those blocks".
"I know it's difficult, but Grenfell changes everything and I just don't believe we can take any risk with our residents' safety and I have to put them first.
"I offered to pay for fire stations to be stationed outside all of those blocks so we could have a couple of days to get the work done but the message was there was absolutely nothing I could do to make those blocks safe that night."
She said that if people still choose to not leave their homes then it would "become a matter for the fire services".
The Chalcots estate's cladding is similar to Grenfell Tower in west London, where a fire is feared to have killed 79 people.
Chalcots was refurbished between 2006 and 2009 by the same firm, Rydon, that oversaw work at Grenfell Tower in 2015-16.
Camden Council says it will remove external thermal cladding from five tower blocks on the Chalcots estate.
It also said there were concerns about the insulation of gas pipes going into flats, and fire doors.