London Fire: 95 U.K. Buildings Fail Fire Safety Tests (Video)

LONDON — Nearly 100 high-rise towers around the U.K. have failed fire safety tests to their exterior cladding conducted after London's deadly apartment block blaze, officials said Tuesday.

The June 14 fire at Grenfell Tower left at least 79 people dead, sent shock waves throughout Britain and plunged the government of Prime Minister Theresa May into crisis.

Cladding added during a recent refurbishment is suspected of worsening the blaze, and May said a "major national investigation" is being conducted into the use of the material.

Officials have pressed landlords to submit samples for testing, with the minister in charge of local government, Sajid Javid, saying he was concerned with the pace of submissions. The facility analyzing the samples can test up to 100 a day.

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FROM JUNE 24: 10 Days After Grenfell Tower Fire, a Scramble to Avoid Another Tragedy 1:58

In addition, inspectors in London's borough of Camden found that hundreds of fire doors were missing in five high-rise social housing blocks. The local government estimated it needed to order 1,000 new fire doors, according to Javid.

"Clearly something has gone wrong there, drastically wrong," Javid told lawmakers in Parliament Monday. "But it's an example of, again where these issues need to be looked at very carefully why this is happening in this day and age in our country."

Cladding has been fitted to the exterior of hundreds of concrete housing blocks built in England the 1960s and 1970s to improve their appearance or insulation. Officials estimate that up to 600 buildings around the country may have cladding similar to Grenfell Tower's.

Contractors at Grenfell used a non-fire-resistant outer layer — a practice not illegal under current British regulations — and it is suspected this material helped the blaze spread rapidly.

The deadly blaze is now the subject of a police investigation and an official public inquiry.

While illegal in the European Union and the U.S., cladding similar to that used in Grenfell Tower may have been used on buildings in other countries around the world, according to experts.

"Regulations aside, [fire safety and materials used in tall buildings] is an international issue," said Matthew Needham-Laing, a leading litigation lawyer and construction expert. "We know of fires in China ... fires in the Middle East, fires in this country and also in France.

Related: 600 High Rises Have Grenfell Style Cladding

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