A leading education expert and adviser to the UK government has claimed that up to 200 Welsh primary schools could close within five years.
Professor Reynolds warns action is needed
Research by BBC Wales' Taro Naw programme, shown on S4C, said education authorities were under pressure to reduce surplus places in their schools.
Professor David Reynolds said policies on closing schools in Wales were very different to those in England.
The Welsh Assembly Government said it was a matter for councils to decide.
On Tuesday evening, the Welsh Local Government Association announced it would review its small schools and surplus pupil places policy.
A cross-party working group, involving local authority members and officers, will meet throughout the summer and is expected to produce a report in the autumn.
Prof Reynolds, of Exeter University, an independent adviser on education to the UK government, told the programme that more thought in Wales was needed to avert closures.
Many rural schools with falling numbers face closure
"If people don't think creatively about how we could support the schools, but instead just proceed to shut them, then I fear that one in six, one in seven of the rural primaries that are small will simply be taken out," he said.
Research carried out by Taro Naw reveals that 403 primary schools in Wales have a surplus of 25% or more unfilled places.
This is the level that the assembly government considers a "significant surplus" - the point at which provision should be reviewed.
The programme includes interviews with the former education director of Carmarthenshire and the head of education services in Denbighshire - two counties where the closing of primary schools has been the subject of heated debate.
Carmarthenshire Council is facing fierce opposition from parents following the publication of their £110m modernisation plan, which could lead to the closure of up to 40 primary schools in the county.
Earlier this year, Denbighshire council was forced to delay plans which could mean 14 primary schools being replaced by a smaller number of new "area" schools.
Former Carmarthenshire education director Alun Davies spoke to Taro Naw before retiring at the end of March.
Defending the modernisation plan, Mr Davies said Carmarthenshire was planning to create 20 new schools. "Communities are going to benefit from this," he said.
Denbighshire's head of education services, Ieuan Lloyd Roberts, said that all education authorities in Wales were facing the same situation as Denbigh.
"I would be very worried," he said. "I wouldn't be able to sleep at night if it was only Denbighshire getting to grips with this situation. Every county is looking at the situation."
In 1998, the Department for Education in England introduced a presumption against closing small rural schools. Since then, on average, only five rural primary schools in England have closed each year.
In 2004 alone, six rural Welsh primary schools closed.
If parents object to the proposed closure of a school, the final decision lies with Welsh Education Minister Jane Davidson.
An assembly government spokesperson said: "Our policy towards rural schools...seeks to strike a balance, supporting and sustaining schools in the challenges they face, but acknowledging that in some cases alternative arrangements, including closure, are in the best interest of learners."
Prof Reynolds said: "I think in Welsh political life and in (Cardiff) Bay also there is a presumption of closure.
"The obsession has been to get the surplus place numbers down."
Welsh Conservatives' education spokesman David Davies said: "Jane Davidson must give a cast iron guarantee that these closures will not happen.
The AM, who is also prospective parliamentary candidate in Monmouth, said: "Labour came to power promising to make education their top priority. The reality is that they have closed down schools left, right and centre."
Plaid Cymru's parliamentary education spokesman Simon Thomas MP said: "These kinds of numbers are truly shocking but confirm that New Labour is intent on tearing the heart out of rural village life.
"Small rural villages need a pub, a post office, and a doctor but, above all, they need a school."
The Welsh Liberal Democrats said: "There is a need to preserve popular and effective local schools. This should take the form of a presumption against the closure of rural schools.
"Schools have a particularly important role in rural communities. In providing the best possible education in rural areas."
Responding to the other parties' criticisms, a Labour assembly government spokeswoman said it had increased education spending by 67%.
"Standards have risen and class sizes have fallen, and there are now 1600 more teachers in our schools in Wales than in 1997," she added.
Taro Naw, Tuesday, 5 April, S4C, 2025 BST