Flammable cladding has been found on 75 high-rise buildings across 26 local authority areas, Sajid Javid has said.

The Communities and Local Government Secretary revealed the safety crisis had further escalated as he urged local authorities to hasten action.

Hospitals and schools will also be tested to make sure they are not encased in combustible cladding, he told the House of Commons.

The so-called combustibility test has been failed by every building tested so far, Mr Javid said.

Grading the material on a scale of fire-resistance, the assessment determines whether the material meets building regulations.

The minister reiterated concerns in Whitehall that councils were not being fast enough in submitting samples for testing.

Mr Javid said: "I can inform the House that as of midday today the cladding from 75 high-rise buildings in 26 local authority areas has failed the combustibility test."

He added: "The combustibility test has three categories rated one to three and it is judged that cladding material in categories two or three does not meet the requirements for limited combustibility in building regulations.

"I can also confirm to the House that, so far, on that basis, all samples of cladding tested have failed.

"The fact that all samples so far have failed underlines the value of the testing programme and the vital importance of submitting samples urgently."

He added: "I am concerned about the speed at which samples are being submitted.

"I would urge all landlords to submit their samples immediately."

The scope of the forthcoming public inquiry into the blaze is expected to widen, examining the apparent widespread use of the cladding.

Theresa May's official spokesman said questions over why the material was used on tower blocks nationwide despite breaching fire safety rules would likely be scrutinised.

"It is clearly a huge concern that this is the case," the spokesman told reporters.

Downing Street earlier said the Department of Health and Department for Education will oversee the testing of schools and hospitals.

Schools and authorities responsible for schools have been contacted across the country and ordered to carry out checks on their buildings.

They have been told any concerns about materials used on school premises should be reported to the Government for investigation.

It is not clear at this stage how many buildings could be affected.