The equality and Human Rights Commission is failing to protect the rights of non-religious people in education despite repeated calls for help, campaigners have warned.
The EHRC, established to fight discrimination, has consistently neglected parents and teachers who do not follow a religious faith, according to the National Secular Society (NSS).
Its criticism of the commission came as Dorset County Council considers a radical reorganisation that would leave some parents with no choice but to send their children to a faith school.
The plan, which would close Swanage First School, has been vociferously opposed by teachers, parents and local campaigners. Jim Knight, the schools minister and local MP, has also called for parents to retain the "fundamental choice" of whether they want a religious education for their children or not.
But the commission has so far refused to offer its backing, despite being lobbied by the society.
Keith Porteous Wood, executive director of the society, said: "Non-religious teachers and pupils from non-religious families - hundreds of thousands of them - are facing increasing discrimination in education.
"It is a pressing human rights issue that we had hoped the commission would be prepared to respond to. Our hope is that the commission will prove to be equally happy to deal with issues for non-believers as believers."
The comments came as councillors in Dorset consider whether to abandon the existing three-tier system - with first, middle and upper schools - and replace it with more conventional primaries and secondaries in a bid to cut surplus places.
Under the plans, Swanage First, rated outstanding by Ofsted, and St Mark's CofE First School would be closed and a new primary opened on a different site.
When a new school is created, different organisations must be allowed to bid to run it. Swanage is thought to be the first example where there has been no bid by a non-religious group.
Nationally, the Church of England already runs about 3,900 primaries and the Roman Catholic Church more than 1,600.
Mr Porteous Wood said he was not "holding his breath" that the EHRC would back the society's campaign. It would fit with similar inaction over issues affecting non-religious teachers, he said.
New rules were introduced last year that allow voluntary-controlled faith schools to discriminate in appointing heads who follow a particular religion.
The NSS called on the commission to back rules that would protect non-religious teachers in faith schools so that their chances of promotion were not damaged.
"Despite repeated requests, it took no action," said Mr Porteous Wood. "Now it's too late and we fear many teachers' promotion prospects, including staff in line for these headships, will be ruined."
In a letter to the commission, the society said it should ensure that parents "have the right to education for their children that conforms with their religious and philosophical convictions" under European human rights law.
It added that choice for non-religious parents should be specifically taken into account when opening schools. It also called for formal parental votes to be run by local authorities when they are considering opening or closing schools or reclassifying their religious character.
A spokesman for the commission said: "The NSS has brought a number of matters to our attention. It is incorrect to say that we have not taken action in any of those cases, or that the commission has a biased approach to the use of its enforcement powers.
"It would be inappropriate for the commission, as a regulatory body, to disclose information about the preliminary stages of any potential enforcement action. To do so could potentially breach the Equality Act, prejudice any subsequent enforcement action that is taken, or adversely damage the reputation of organisations which might or might not be subject to enforcement action."
Powers that be
The EHRC was established in October 2007, taking over the work of the Commission for Racial Equality, the Disability Rights Commission and Equal Opportunities Commission.
It also assumed new responsibilities over areas including religion or belief, sexual orientation and age.
Chaired by Trevor Phillips, the commission aims to eliminate discrimination.
It has enforcement powers that it can use to guarantee equality.