New government plans to allow faith schools to teach sex education in line with their religious beliefs have come under fire from gay charities.

Under the recommendations of the review, all schools will be forced to teach sex education.

However, faith schools will be allowed to present lessons in line with their own “context, values and ethos”.

This will allow them to tell pupils that homosexuality, sex outside marriage or using contraception is wrong.

In a letter to schools secretary Ed Balls, George Broadhead of the Pink Triangle Trust claimed that allowing faith schools freedom to teach what they choose will lead to an increase of homophobic bullying.

Mr Broadhead wrote: “Homophobic bullying plagues the majority of UK schools and shocking levels of bullying are meted out to school pupils and teachers who either are gay or perceived to be gay. That is the conclusion of a wide-ranging study carried by gay equality organisation Stonewall.

“The study found that nearly two thirds of LGB pupils reported instances of homophobic harassment and this figure jumps to 75% for those attending faith schools.

“It is surely unacceptable that a large proportion of our schools should be allowed to tell pupils (in line with the teaching in their holy books) that homosexual relationships are morally wrong, with the inevitable consequence that anti-gay bullying will increase.”

He added: “When this survey was issued, you yourself pledged to stamp out all forms of bullying in schools.”

The Gay and Lesbian Humanist Association (GALHA) has also expressed concern, saying that the proposal was “extraordinarily ill-thought out”, saying it would give a “green light” to homophobic bullies.

GALHA Secretary David Christmas said: “If the government wants a generation of young gay people to grow up who feel isolated, embittered, and alienated from the rest of society, then they are going the right way about it.

“Ideally, state funding of religious schools should be phased out. Failing this, the least that we as taxpayers should expect is that schools be required to offer relevant education and support to all of their pupils, including those who are, or may be, gay and lesbian.”

The government-commissioned review was authored by Sir Alasdair Macdonald, headteacher of Morpeth School in east London.

It concluded that schools will be legally obliged to teach pupils about health and nutrition, safety, drugs and alcohol and sex education.

Other subjects on the core curriculum will include tackling cyber bullying and teaching pupils how to manage their bank accounts.

Despite plans to make it compulsory for schools to teach on sex education, parents will still be allowed to withdraw their children from lessons.

The schools secretary, Ed Balls, has accepted the proposals and said they will now be subject to consultation.