The British government is urgently conducting safety checks on an estimated 600 high-rise buildings in England which have exterior cladding panels, according to officials.
It comes after at least 79 people died when fire consumed a London tower block last week.
Cladding, added during a refurbishment of Grenfell Tower, may have played a part in the 14 June disaster when flames sped through the 24-storey residential building, trapping people inside, residents have said.
The blaze in the London borough of Kensington and Chelsea, Britain's worst since World War Two, has heaped pressure on Briths Prime Minister Theresa May.
The Grenfell tragedy has acted as a focal point for anger at local authority funding cuts. There have been accusations of criminal negligence and, if more buildings are deemed unsafe,the government faces the task of rehoming people within existing social housing facilities which are stretched.
"The estimate provided to us by councils is that there are approximately 600 high-rise buildings with similar cladding," Mrs May's spokeswoman told reporters. She said the government had no estimates yet for Scotland, Wales or Northern Ireland.
Cladding panels are often added to the exterior of buildings to insulate them and, particularly in the case of ageing tower blocks, to improve their external appearance.
The panels vary in terms of their fire resistance depending on their intended use.
"In terms of the people who are living in those buildings,we will do a further test to make sure the buildings are safe - obviously nobody will be living in buildings that are unsafe," Mrs May's spokeswoman said, adding that people would be rehoused if necessary.
A spokesman for the communities and local government department, the office in charge of testing the buildings, later said that the 600 figure was an estimate of how many had any form of cladding and not an indication of how many would eventually be found to be dangerous.
Earlier, Mrs May announced that cladding used on some buildings had been found to be combustible with her local government minister saying 11 had so far tested as combustible.
"(We) should of course be careful on speculating what caused this fire, but as a precaution the government has arranged to test cladding on all relevant tower blocks," she told parliament.
"I was informed that a number of these tests have come back as combustible."
She said local authorities and fire services were taking steps to make affected buildings safe and to inform residents.
Mrs May has launched a public inquiry into the fire and police have announced a criminal investigation. Tests on the cladding of Grenfell Tower would be made public in the next 48 hours, she said.
Inquests were opened and adjourned at Westminster Coroner's Court into the deaths of five victims, with a married couple officially named as among the dead.
Omar Belkadi, 32, died from inhaling fire fumes, while his wife, Farah Hamdan, 31, was killed by smoke inhalation.
They lived on the 20th floor of Grenfell Tower with their daughters Malek, seven, Tazmin, six, and six-month-old Leena.
The two eldest daughters were found in hospital by family members but the fate of baby Leena remains unknown.
Abufars Ibrahim, 39, died of multiple injuries, while Anthony Disson, 65, and a 52-year-old woman, Khadija Khalloufi, both died from inhalation of fire fumes.
A highly toxic gas released by insulation on the outside of the building may have contributed to deaths.
Yesterday, a funeral for 23-year-old Syrian refugee Mohammad Alhajali, the first victim to be identified, was attended by his family and London Mayor Sadiq Khan.