Members of the Save Our Services group are seeking assurances that developers building on former school land will provide new playing fields for community use.

If no such "community access agreements" are made to guarantee open spaces will be provided, the group plans to pursue the matter in the courts.

The plans were discussed by the borough council regeneration scrutiny committee.

Councillor Tony Clarke (Ind, Castle), who supported them, said: "We have asked for an investigation into the failure of the borough council, County Council and the West Northamptonshire Development Corporation (WNDC) to put into place these community access agreements.

"The borough council approved the county council and WNDC's plans to sell off school sites, but only on the condition that these agreements were made.

"If sales are approved without the agreements being in place, planning applications could be called in for a judicial review, which would put a huge spanner in the works."

The county council struck a £90 million deal with Barratt Homes last year, to sell off 16 former school sites to fund school-building.

That deal suffered a blow last month when the Government ruled playing fields at one school – Parklands – must be preserved.

Plans to develop each site are now being agreed on an individual basis. But according to Save Our Services spokesman Dave Green, these deals could be in doubt if the access agreements stipulated by the borough council are not adhered to.

He said: "Steps must be taken to stop development on sites already given planning permission under the illusion that access agreements would be drawn up."

Councillor Andrew Simpson (Lib Dem, Kingsley), the chairman of the regeneration scrutiny committee, said the borough cabinet had been asked to investigate whether access agreements had been put in place, but added that a judicial review was a last resort.