A lawyer acting for campaigners trying to save six rural schools from closure has claimed Powys council may not be following its own policy.
Campaigners say they are prepared to fight the closures in the courts
Welsh Assembly Government guidelines on small schools may also have been breached, Michael Imperato has claimed.
The council dismissed the claims and said it had been open about its primary school policy, adopted in January 2006. The schools are facing closure after a council review found there were more than 4,000 surplus primary places.
The future of the six schools - Howey Church-in-Wales School, Llangurig CP School, Llanfihangel Yng Ngwynga Church-in-Wales School, Ysgol Gynradd Carno, Ysgol Efyrnwy and Ysgol Thomas Stephens - will be decided on 9 October.
Mr Imperato said if the council had breached its own policy and that of the assembly government's, there were "real prospects" campaigners would succeed in a judicial review challenge to halt the closures.
"There is a real concern amongst the campaigners that the council has picked these schools simply because they are small," he said.
The lawyer, who was engaged in the unsuccessful legal challenge to the closure of Hermon School in Pembrokeshire in 2004, confirmed he had contacted the council with the hope of entering into "some kind of dialogue".
But a spokesman for the council said it had been "completely open about the pressures created by surplus places and the need to tackle the high cost of maintaining some schools".
He said: "The council adopted a new primary schools policy in January last year (2006), a policy that was approved after widespread public consultation and support.
"We are now implementing that policy and following processes clearly set down. Claims that we are not following our own policies are nonsense."
Dr Roger Blunden, governor of one of the affected schools and a member of the Powys Campaign for School Action said they hoped that legal action would not be necessary but they were "fully prepared" to fight the issue in the courts.
August 2008 is expected to be the earliest date for the proposed closures.
Parents from the schools affected have protested outside council offices and attended a public meeting.
The Farmers' Union of Wales (FUW) added their support to the parents and governors' campaign, claiming rural communities in Powys would be damaged if the closures went ahead.
The closures were first announced after a council review found that costs at smaller schools were higher.
David Jones, Powys Council's board member in charge of schools, said that funding per pupil in a small school was £5,000 per head more than at an average school, where the cost is £3,000 per pupil.
Plans to close a dozen Powys schools in 2003 were shelved after opposition.