Campaigners for LGBT issues have accused the government of refusing to abolish "get out clauses" from discussing homosexuality with children, which they say "give schools a licence to promote bigotry".
Schools Out, a group that has been campaigning for Lesbian, Gay, Bisexual and Transgender (LGBT) equality in education since 1974, argue there should be greater emphasis on the ned to promote equal opportunities.
Tony Fenwick, co-chair of the group, said he welcomed the fact that the Equality Act 2010, which prohibits individual discrimination, covers the way school curriculum is taught and that it states schools must ensure the needs of all pupils are met. But he added "beyond that everything seems to be optional".
"The words 'encouraged to' and 'non-statutory guidance' simply mean that schools have the possibility of opting out of promoting equality for LGBT people if they so wish.
"The words 'should take account of the ethos of the school' suggests a faith ethos can allow a school to override the requirements of the Act," he added. "These get out clauses could give schools a licence to promote bigotry."
Education secretary Michael Gove was recently at the centre of a row over how faith schools discuss homosexuality in sex education after claims a US preacher had distributed "homophobic material" at Roman Catholic schools.
At the time, Gove insisted the Equality Act did not apply to the school curriculum, according to reports by the Guardian.
When Fenwick, the co-chair of Schools Out, contested Gove's views, he did not receive a "specific reply" but was sent the letter the Barber received from the education secretary in 2011.
The letter, addressed to the TUC's general secretary and signed by the minister, states: "The education provisions of the Act which prohibit discrimination against individuals (including their sexual orientation) do not extend to the content of the curriculum.
"I would like to reassure you that all schools are encouraged to provide a broad programme of Sex and Relationship Education (SRE).
"Schools, however, have discretion in what is taught within Personal, Social and Health Education (PHSE) and how it is taught. Schools should take into account the ethos of the school, as well as the views of parents and pupils."
Gove adds in the case of faith schools, the only requirement is for them to teach the statutory science curriculum, as well as AIDS/HIV education as part of SRE.
But it is not all bleak news: the organisation is celebrating the success of its online lesson plans and resources for teachers who want to deal with LGBT issues in the classroom. Despite LGBT History Month having passed, nearly 500 teachers viewed the resources which are hosted on the Times Educational Supplement website.