Some 104 schools and colleges are scrambling to put emergency measures in place in time for the return after the summer holidays after being told by the Department for Education (DfE) to partially or fully close buildings.
It is because of fears concrete used in their construction could collapse.
However, the Government has not revealed the 104 education facilities that are affected.
Oxford West and Abingdon MP Layla Moran said she feared the problems with reinforced autoclaved aerated concrete (RAAC) could even be far wider.
She said: “We know that the government have identified around 600 schools that need assessing. My understanding is that only about a third have been so we need a full transparency mechanism for parents.”
Councillor Sean Woodcock, leader of the opposition Labour group on Cherwell District Council has written to Education Secretary Gillian Keegan demanding all the schools are named.
He wrote: “With just days to go before the start of the new term parents have got enough to worry about without having to find out if their child’s school is safe.
“It is staggering that ministers have waited until now to act on this issue, and it is appalling that thousands of children face chaos and disruption to their education because they cannot start at their own school next week.
“The secrecy around this announcement has caused huge concerns – it is now vital that you come clean.”
Mr Woodcock asked for “clear and unequivocal guarantee to parents in Cherwell that ALL schools – including academies, free schools, and nurseries – have been properly assessed and that children are not at risk”.
A spokesperson for Oxfordshire County Council said all secondaries in Oxfordshire, bar one, are now academies and a large number of primaries are also academies.
As such the council is not responsible for them.
Nonetheless schools are asked to update the Emergency School Closures on the council’s website if they need to close for any reason.
Currently none have listed themselves as needing to be closed.
The government said it took the action after seeing new evidence that showed 52 of the 156 educational settings containing the concrete had taken protective steps so far this year.
The DfE said a “minority” will need to “either fully or partially relocate” to alternative accommodation while safety measures are installed.
But its guidance to schools said funding will only be provided for works that are “capital funded” and schools will have to pay for rental costs for emergency or temporary accommodation.
RAAC is a lightweight building material used from the 1950s up to the mid-1990s, but now assessed to be at risk of collapse.
The DfE has been considering RAAC as a potential issue since late 2018 but the timing of the decision to issue guidance just days before the start of term has angered unions.
National Education Union general secretary Daniel Kebede said: “It is absolutely disgraceful, and a sign of gross Government incompetence, that a few days before the start of term, 104 schools are finding out that some or all of their buildings are unsafe and cannot be used.
“To add insult to injury the Government states in its guidance that it will not be covering the costs of emergency temporary accommodation or additional transport.”
Ms Keegan insisted that a “cautious approach … is the right thing to do for both pupils and staff”.
“Nothing is more important than making sure children and staff are safe in schools and colleges, which is why we are acting on new evidence about RAAC now, ahead of the start of term,” she said.
“The plan we have set out will minimise the impact on pupil learning and provide schools with the right funding and support they need to put mitigations in place to deal with RAAC.”