Experts have warned that the crisis over reinforced autoclaved aerated concrete (RAAC) could extend beyond the education sector - with healthcare settings, courts and offices also potentially at risk.

RAAC is a lightweight building material used from the 1950s until the mid-1990s which has now been assessed to be at risk of collapse.

One school in East Sussex is understood to be affected by the unsafe concrete, with urgent inspections underway to determine if any parts of the building need to be closed.

Schools in Brighton and Hove and West Sussex are unaffected by the issue.

Opposition parties are demanding information about the scale of RAAC across the public sector estate, with Labour calling for an “urgent audit”.

The Liberal Democrats have also called for “urgent clarity” over whether hospital wards and other buildings could be forced to close.

Engineers have warned that the problem could also affect hospitals, prisons, courts and offices due to the use of RAAC until the mid-1990s.

Though not confirmed, it is estimated that around 24 schools in England have been told to close entirely due to the presence of RAAC, but schools minister and MP for Bognor Regis and Littlehampton Nick Gibb admitted more could be asked to shut classrooms.

Mr Gibb said that a collapse of a beam that had been considered safe over the summer sparked an urgent rethink on whether buildings with aerated concrete could remain open.

He insisted schools were contacting affected families and told the BBC’s Today programme that the government would publish a list of affected schools, but only once they are in a “stable place”.

Chairwoman of Parliament’s public accounts committee Dame Meg Hillier warned RAAC is just the “tip of the iceberg” and questioned why schools had been “left to deteriorate for so long”.

She told Times Radio: “In both schools and hospitals, there hasn’t been enough money going into buildings and equipment.”