Dozens of schools across England have been forced to close at the start of the new academic year due to fears over reinforced autoclaved aerated concrete (RAAC).

Used as a building material between the 1950s and 1990s, there are now concerns that schools with the concrete could pose a danger to pupils.

Greenway Junior School in Horsham will be closed tomorrow as a precaution as “the presence of RAAC cannot be ruled out”.

A spokesman for GLF Schools, which operates the school, said that there is “no confirmed RAAC” at the school but some areas of the building will be out of use until further surveys are complete.

“Parents have been advised that the school will be closed on Tuesday to allow for arrangements to be put in place and will be updated further in due course,” he said.

The news came after East Sussex County Council confirmed on Friday that a school in East Sussex has also been confirmed to have the unsafe concrete by the Department for Education.

The as-yet-unnamed school is undertaking an urgent inspection of the site and reviewing if any parts of the building need to be closed.

West Sussex County Council is also organising a physical inspection of all schools it maintains that were built between 1930 and 2000.

No schools maintained by Brighton and Hove City Council are believed to be affected by the RAAC crisis.

However, a Sussex MP has now said that a third education setting has expressed fears that it may also have RAAC.

While Sally-Ann Hart, the MP for Hastings and Rye, said there have been no confirmed cases of the unsafe concrete in her constituency, she said: “One education setting is concerned that it may have RAAC and is awaiting a survey”.

Ms Hart urged any school concerned about the concrete to inform the Department for Education.

She described the decision to close some schools as a “precautionary step” and said: “I understand that support and updated guidance is being given to schools - nothing is more important than the safety of our children.”

The Argus has contacted East Sussex County Council for comment on Ms Hart's claims.

Chancellor Jeremy Hunt said the government will “spend what it takes” to make schools safe.

He also sought to reassure parents that an “exhaustive process” has been carried out to identify any unsafe buildings, but admitted that, along with the potential danger of RAAC, there are also concerns about the possibility of a “wider” problem with asbestos in the nation’s schools.

Schools minister and MP for Bognor Regis and Littlehampton Nick Gibb said that more classrooms could be forced to shut, with the Chancellor confirming further structural problems could emerge in the coming “weeks or months”.

Mr Hunt told Sunday with Trevor Phillips on Sky News: “We have 22,000 schools in the country and there has been since that incident a huge programme going through this RAAC/asbestos issue because we want to be absolutely sure that every child is safe.”

Gillian Keegan, education secretary and MP for Chichester, has promised the crisis will not lead to a “return to the dark days of lockdown”, despite guidance advising schools to use pandemic-style remote learning as a last resort if they are unable to hold face-to-face lessons.

Writing in the Sun on Sunday, she said there was “no choice” other than closures after a “handful of cases” where RAAC had failed.

Ms Keegan said parents should still send their children to school unless they have been told otherwise.

She said: “The schools impacted by this issue will contact parents to let them know if there is any change to the start of term.

“Most schools will be unaffected and children should attend school as normal in September unless you hear differently from the school.”

Remote learning for children unable to access face-to-face lessons should last “days, not weeks”, the government has said, but ministers have refused to indicate exactly when the disruption might ease.

Education leaders have been encouraged to use community centres, an “empty local office building” or other schools for the “first few weeks” while structural supports are installed to mitigate the risk of collapse.