Tests have revealed that at least seven tower blocks across England are fitted with combustible cladding.
Among them are the Chalcots Estate in Camden, north London, where the cladding is being removed, and the Mount Wise Tower in Plymouth.
Theresa May said local authorities and fire services are “taking all possible steps” to ensure the towers are safe, while hundreds more buildings are due for checks.
Details of at-risk structures will be revealed after residents are informed, the Department for Communities and Local Government says.
Cladding on the outside of Grenfell Tower is suspected to have hastened the spread of the blaze which killed at least 79 people.
Earlier, Downing Street said 600 buildings in England had “similar cladding”, but it was later confirmed that there are 600 high rises with any form of cladding.
The Government is performing tests on 100 tower blocks a day, with results coming back “within hours”, Mrs May said.
A Number 10 spokeswoman said residents of affected buildings could be rehomed if the blocks are found to be unsafe after further tests.
In a statement to the Commons, Theresa May said that the chair of the inquiry into the Grenfell Tower disaster will produce an interim report “as soon as possible”.
Former Labour deputy leader Harriet Harman said the results of cladding tests were “chilling” and called on the Prime Minister to “get a grip on this personally”.
The Grenfell Tower disaster would have been avoided if the Government had acted on the findings of an inquest into the deaths of six people in the 2009 Lakanal House fire, Ms Harman added.
Kensington MP Emma Dent Coad told Mrs May residents in her constituency had been left “traumatised and frightened” after the Grenfell fire.
Earlier, the chief executive of Kensington and Chelsea Council resigned following criticism of the authority’s reaction to the tragedy.
Nicholas Holgate said Communities and Local Government Secretary Sajid Javid had “required the leader of the council to seek my resignation”.
London Mayor Sadiq Khan said: “I welcome the resignation of the chief executive. It’s still not enough.
“I think it’s not sustainable for those in positions of power and influence in Kensington and Chelsea to stay there bearing in mind the lack of confidence from those residents.”
