Shock cutbacks to a national school-building programme will leave all but a handful of projects cancelled, its former director has warned.
Last week education minister Leighton Andrews announced that the 21st Century Schools programme, a unique collaboration between the Welsh Government and local authorities, would not go ahead as planned.
The minister told town halls to re-submit plans to improve their school buildings and said they would have to provide more cash in future, contributing 50 per cent of the project funding instead of the previous 30 per cent.
Speaking exclusively to TES Cymru, former 21st Century Schools programme director Martin Lipson said: "Very few local authorities will be able to go ahead now - perhaps two or three at the most.
"There are many more schools in a serious condition than there ought to be. You wouldn't want to send your children to some of these schools.
"There are schools in urgent need of investment - within the next year in some cases - that will not now get the repairs they need. That is a very serious concern for pupils, parents and teachers."
The Government started working on the ambitious programme in 2008 to address historic under-investment in Wales's school buildings, encouraging local authorities to rationalise their school stock and remove surplus places.
The collaboration was formally launched last year and it was expected that most, if not all, councils would start building projects within four years.
But speaking to Assembly Members last week, Mr Andrews said: "The environment has changed. There has been a sharp reduction in capital funding imposed on the Welsh Government. of 40 per cent across the current funding period.
"Against that background. authorities must be given the opportunity to review the timing and content of their planned investments so as to take the hard decisions early that will ensure funding goes to the delivery of excellence in education, not the maintenance of buildings."
A national survey of school buildings carried out last year found that only 63 per cent are in a reasonable condition and almost 2 per cent are at the end of their operational life. It is estimated that around pound;5 billion is needed over the next 12 years to bring Wales's schools up to scratch, but so far the Government has only committed to pound;415 million of funding for 66 projects, including 26 new schools.
The Welsh Local Government Association (WLGA) said the gap between the money available and the scale of the challenge is now "completely out of kilter".
Peter Fox, the WLGA's lifelong learning and skills spokesman, said: "The decision to move to a 50 per cent rate of capital grant is of great concern to all councils as their capital and revenue budgets are already under significant pressure.
"We need to examine all potentially new sources of funding available to update our schools' stock and to ensure the right provision in the right place for the future."
Mr Lipson said local authorities would be justified in feeling let down by the situation. "We held meetings all over Wales where we encountered very sceptical elected members, and we convinced them that the Government meant business," he said.
"That trust is now evaporating. The Government keeps making promises it can't deliver. There's no need for local authorities to rethink - they have already put a lot of thought into what needs to be done."
Mr Andrews' decision has provoked anger from the education sector.
Dr Philip Dixon, director of education union ATL Cymru, said: "The provision of a decent learning environment for children is essential for their educational development. It is imperative that what limited funds are available are now targeted to best effect where they will make most impact."
Educational consultant Terry Mackie, a former head of school improvement for Newport council, said: "This is a very dark day in Welsh education. The minister's decision to suspend the bidding and tendering process is catastrophic.
"This is a gross failure of innovation and strategic planning. It is now difficult to see 21st-century educational standards being achieved in any sustainable way across the nation."
The Welsh Government said it remains committed to delivering schools that are fit for the 21st century. A spokesman said: "This was never intended to be a `big bang' approach, but a long-term programme of investment."