Some schools in England will have to relocate teaching until safety measures can be put in place.
Schools in England must immediately shut buildings made with a type of concrete that is prone to collapse until safety measures are in place, the government is expected to announce.
Some schools will have to relocate children to other teaching spaces.
More than 100 schools are being contacted before the start of new term.
Safety measures include propping up ceilings in buildings made with reinforced autoclaved aerated concrete (RAAC).
The Department for Education (DfE) has not given a timeline for replacing the RAAC, but school leaders have called for an “urgent plan” to fix buildings.
A report by the National Audit Office (NAO) in June assessed the risk of injury or death from a school building collapse as “very likely and critical”.
It highlighted concerns for school buildings that still contained RAAC- a lightweight form of concrete prone to collapse, used widely between the 1950s and mid-1990s.
The report said the DfE had identified 572 schools where RAAC might be present and that 65 had been confirmed, of which 24 required immediate action.