Urgent action must be taken by the Government to ensure deteriorating school buildings “at risk of collapse” are made safe, unions have said.

In an open letter to Education Secretary Gillian Keegan, a coalition of seven unions has asked the Government to set out the measures taken to eradicate the risk of collapse of buildings to ensure the safety of pupils and staff.

Deteriorating school buildings could end up “costing lives” if the Government does not take action to carry out repairs, a school leaders’ union has warned.

The letter – from the National Education Union (NEU), school leaders’ union NAHT, the NASUWT teaching union, Unison, Unite, GMB and Community – says it is “shocking” that a Department for Education (DfE) report acknowledged that some school buildings are at risk of collapse.

“Perpetual under-investment in the school estate has led to deteriorating buildings,” the letter from union leaders adds.

The DfE’s consolidated annual report and accounts, published in December last year, said: “There is a risk of collapse of one or more blocks in some schools which are at or approaching the end of their designed life-expectancy and structural integrity is impaired.

“The risk predominantly exists in those buildings built in the years 1945 to 1970 which used ‘system build’ light frame techniques.”

The direction of travel for this risk is assessed by the DfE as “worsening”.

Highlighting the DfE report, the letter from union leaders says: “This is a truly shocking admission. We have reached absolute rock bottom.”

Kevin Courtney, joint general secretary of the NEU, said: “It is disgraceful that over the last decade of austerity our school buildings have been allowed to deteriorate to the extent that some are at risk of collapse, and the Government does not even know which buildings fall into this category.

“In one of the most advanced economies in the world it is shocking that many children, young people and school staff work and learn in an environment that is dangerously unsafe.”

The union leaders have urged the DfE to publish a full list of buildings at risk of collapse and to set out when affected buildings will be made safe.

Paul Whiteman, general secretary of the NAHT, said: “This is a disaster waiting to happen, which in the worst-case scenario could end up costing lives unless the Government wakes up and acts.

“That means demonstrating national leadership – identifying and being transparent about buildings at risk, ensuring the safety of pupils and staff using them, and implementing an urgent action plan to carry out repairs supported by a massive increase in investment.”

Dan Shears, GMB national health, safety and environment director, said: “It’s no great surprise that schools are in poor condition – we have had a lost decade of under-investment – but to discover that schools are in danger of literally falling down is absolutely scandalous.”

Patrick Roach, NASUWT general secretary, said: “School staff and parents deserve and need to know if their schools are at risk and what is being done to urgently to ensure the safety of their schools.”

A DfE spokesperson said: “We take the safety of pupils and staff extremely seriously. The Department works closely with schools and responsible bodies to ensure all schools buildings are well maintained and safe.

“If the department is made aware of a building that poses an imminent risk of collapsing, immediate action is taken to ensure safety and remediate the situation.

“At present, the Department is not aware of any school building that remains open in this state and would expect responsible bodies to immediately approach us if this were the case.”