The religious ethos of Church of England schools is under threat as they are "wooed" by non-faith institutions to join clusters of academies, church leaders have warned.
Church authorities are worried that federating with non-faith partners will undermine their schools' Christian foundation, prompting plans for their own multi-academy trusts.
These proposed groups would allow church schools that want to switch to academy status to work together and draw on economies of scale without losing cherished links to the diocese.
Peterborough diocese confirmed this week that several of its primary schools have been approached by non-faith secondaries in the area about forming federations.
The Venerable Christine Allsopp, Archdeacon of Northampton and chair of the Peterborough Diocese Board of Education, warned of the "danger" for the 100 church primaries in her diocese.
"Our concern is that small schools, which are vulnerable in the new climate, are being wooed by secondary schools without a church foundation," she told The TES.
"They see the advantage of having a cluster of primary schools joined with them in some way, and that causes us problems because it would compromise the trust basis of schools with a Christian foundation."
The Anglican and Catholic churches have been wary of the expanding academies programme, fearing greater independence for their schools would damage diocesan links.
But significant numbers of faith schools are now set to convert after church authorities struck a deal with the Government over land ownership and the power of dioceses to appoint governors.
Dioceses are concerned that unless they get their own arrangements in place, small church schools that become academies will be tempted into non-religious federations as a way of getting extra support.
"These are enormous issues for us," said Archdeacon Allsopp. "As ever, we are seeking to respond to an agenda that's not our own and having to do that quickly, which is always difficult.
"It's important our primary schools know this is in progress, but there are still many questions to be answered around how we can actually produce what we need in order to safeguard our schools."
In an interview with The TES earlier this year, the Bishop of Oxford, the Rt Rev John Pritchard, who chairs the CofE's national board of education, said that dioceses could offer services to their own schools and to non-faith academies.
Russell Hobby, general secretary of heads' union the NAHT, said some schools have to be ready for added administrative burdens if they become academies.
He said: "Some heads do feel the pressure (to convert), although it's mostly self-imposed. There's a fear that you have to do it quickly or miss the boat for more funding.
"I would encourage heads to do what's right for your school's values; don't do it in terms of the various persuasions that are being offered. Don't feel there's an overwhelming force. Schools need to be reassured that the traditional school model is still a viable one."
Up to 70% will make switch
Thousands of Church of England schools are likely to become academies in the next five years, according to the Bishop of Oxford, who chairs the church's national board of education.
In an interview with The TES earlier this year, the Bishop predicted that up to 70 per cent of the CofE's 4,800 schools will switch to academy status.