The biggest teaching union began a legal challenge yesterday against new rules it fears will allow faith schools to sack homosexual teachers.
The National Union of Teachers (NUT) is to seek a judicial review of the regulations, which implement an EU directive, arguing that they break European law and the 1998 Human Rights Act.
The EU directive allows an employer to discriminate on the grounds of sexuality or religious belief if it was a "genuine and determining occupational requirement, provided that the objective is legitimate and the requirement is proportionate".
Doug McAvoy, NUT general secretary, said a teacher's sexual orientation was irrelevant to his or her ability to do the job. The union is concerned that homosexual teachers in faith schools could be discriminated against by "misinformed and over-zealous" governing bodies.
"We cannot accept that committed teachers should be discriminated against because of their sexual orientation," Mr McAvoy said. "Teachers are professionals working to the utmost of their talents for the benefit of their pupils."
The Department for Trade and Industry argues that the regulations are consistent with European law and the Human Rights Act. A spokeswoman said: "They are a major step forward in combating discrimination at work. Currently there is no statutory pro- tection against discrimination for lesbians or gay men.
"It would be unlawful for governing bodies to sack good teachers simply on the grounds of their sexual orientation, as the NUT claim."