By politics.co.uk staff
Faith schools insisting that their teachers come from a specific religious background could leave the government open to discrimination claims.
Law firm Beachcroft LLP has said "strong grounds" exist that proposals contained in the education bill setting up academies independent of local authorities could breach EU law.
Education secretary Michael Gove plans to increase the quota of staff hired on religious grounds at the new academies from 20% to 100%.
Existing staff could find themselves forced out of a job or barred from promotion as a result.
"The statutory protections on which the jobs of hundreds of thousands of non-religious teaching and support staff depend will be clandestinely removed when they transfer to academies," Keith Porteous Wood, director of the National Secular Society, said.
"Staff should be treated with equal respect whatever their faith or lack of it and not be forced into pretending to hold beliefs that they do not have, in order to retain their jobs.
"This has the potential to be the most serious erosion of religion and belief employment rights."
The Department of Education has said it is confident the proposals do not breach any domestic or European law, however.
But Beachcroft LLP's advice stated: "There are strong grounds to believe that the government's proposals are a breach of its legal obligations to protect teachers (and others) from discrimination on the grounds of religious belief - set out in the [EU] directive."
The education bill is currently working its way through the Commons. MPs will begin scrutinising the bill on a clause-by-clause basis in committee stage on March 1st.