Experts believe the new panelling, which contained insulation, helped spread the flames quickly up the outside of the public housing tower.
The number of people killed in London's Grenfell Tower inferno climbed to 79 - but may rise even further, police said Monday.
He says it may be necessary for numerous outmoded tower blocks built in the 1970s to be demolished because of safety concerns.
"It will be imperative that the causes of this fire are fully investigated to determine how such terrible tragedies could be avoided in the future".
Some families have lost more than one member, he added.
The British Metropolitan Police on Sunday released new images from inside the Grenfell Tower, which was gutted in a massive fire last week. Authorities had warned earlier that some of the victims may never be identified because of the state of their remains.
Finance minister Philip Hammond said the inquiry would examine whether the regulations banning certain types of cladding were right and whether they were complied with. Aside from the cause of the fire, officials will look into the building's safety measures and how it was maintained.
Reports suggest that a renovation project on Grenfell Tower previous year intentionally did not include safety devices such as sprinklers and doors created to keep the fire from spreading.
While Mrs May praised the emergency and health services for their heroism, she said support on the ground for families in the initial hours after the disaster was "not good enough". "We will go where the evidence may take us. It will also be a subject that the criminal investigation will be looking at".
"We naturally welcome funds for those in need, though this does show once more the tendency to sideline residents' views", the residents said in a statement, the paper reported.
He said there are roughly 2,500 similar apartment towers throughout Britain.
British Chancellor Phillip Hammond has told the BBC the reportedly cheap, flammable cladding fitted to London's Grenfell tower is banned in the United Kingdom, as authorities continue to investigate whether it contributed to the speed and spread of Wednesday's deadly blaze.
Frustration has been mounting in recent days as information about those still missing in the blaze has been scanty and efforts to find temporary housing for the hundreds of now-homeless tower residents have faltered. "Equally there may be people who were in there that we believe are missing that did escape but for whatever reason have not let it be known that they're safe and well, so again I would appeal to them directly".
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