The leader of Bristol's secondary school headteachers has refused to rule out a legal battle to block plans to open Britain's biggest free school in the city.
Clare Bradford, chair of the Bristol Association of Secondary Headteachers and Principals, said she would take court action if ministers gave the go-ahead to the Bristol Free School.
Education secretary Michael Gove is currently considering whether to approve the free school, which hopes to open with 150 pupils, making it the largest of around 16 free schools expected to open in September.
The proposed school has already come under flak from heads at nearby secondary schools who have accused the school of trying to poach their pupils, and have written a joint letter to the Government objecting.
Ms Bradford, headteacher of Henbury School, which is one of the secondaries closest to the proposed free school, said she would be willing to put in a legal challenge, as she felt the school would be "socially divisive".
"My primary concern is the impact it will have on the social cohesion of the area. If you create a school that is just for a certain community then we are going to end up with problems. I think it will just end up being a middle-class school for middle-class parents," she said.
And she added: "The best outcome would be that Michael Gove rules that the school did not follow the proper procedures, and they put back any decision for a year and they reduce the size of the school. But if that does not happen, then we will consider the possibility of a legal challenge."
Ms Bradford's comments followed a letter signed by a group of Bristol's secondary school heads and principals, who outlined a raft of reasons as to why the free school was not needed in the city.
The signatories said there was insufficient consultation on the proposal and questioned whether a new school was needed when those nearby have a surplus of places.
The letter read: "This year in Bristol, we have a situation where the number of pupils leaving Year 6 is the lowest in years. It is against this background that the Bristol Free School is wishing to add another 150 places to what is already a surplus of places."
And it added: "We would urge the Secretary of State not to enter into a funding agreement with the Bristol Free School for this September, in the interests of safeguarding the education and social cohesion of young people across all Bristol schools."
Bristol Free School chairman Blair King said: "We are surprised and disappointed by the Bristol Association's letter and cannot comment yet on the extent to which it accurately reflects the views of each member.
"Primary school headteachers in North Bristol have been very supportive of the Bristol Free School - as they are of other secondary schools.
"The Bristol Free School was set up in response to overwhelming parental demand for a secondary school in (the area) (a campaign that has lasted for 20 years) because there are five primary schools but no secondary school in our community."
Most say no
In an online straw poll taken by The TES last year, teachers proved to be extremely cynical of the potential benefits of free schools.
When asked whether free schools would have a positive impact on the wider school system, only 7.7 per cent of respondents answered "agree" or "strongly agree". About half of respondents "strongly disagreed".
At the time, the NUT said the findings provided further evidence of the public's "growing discontent". The union's general secretary, Christine Blower, said: "This straw poll is yet another clear indication that Michael Gove's policies on academies and free schools are simply not wanted by the general public.
"To have any hope of continuing in office, the Government needs to listen to the growing discontent around them."
But the education secretary responded that "schools want the freedom to decide what is best for pupils".
"They want to be free to innovate in the classroom, inspiring pupils to learn," he said. "There are now hundreds more academies and many more will follow."