New plans to force all schools to teach sex education will allow faith schools to educate pupils in line with their religious beliefs.

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

The plans, published yesterday, will require schools to teach sex education from the age of five.

However, a get-out clause for faith schools will allow them to present sex education “in line with the context, values and ethos” of the schools.

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

It concludes 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.

Sue Sanders of LGBT campaigning group Schools Out said: “It’s fudging. It is supposed to be compulsory so it should be compulsory.

“It is the schools’ duty to enable pupils to learn about diversity and equality but they can’t do this if parents are permitted to remove their children from lessons.

“It is giving kids a double message.”

The National AIDS Trust welcomed the review but expressed concern that gay young men, especially those in faith schools, were less likely to receive the same level of sex education as their straight peers.

Deborah Jack, chief executive of NAT, commented: “We are concerned, however, that young gay men may not be given the same level of sex and relationships education as their heterosexual peers and education for them will vary from school to school; particularly given the discretion proposed for faith schools.

“HIV diagnoses among young gay men (16-24) have more than doubled in recent years, from 128 in 1998 to 281 in 2007. With HIV diagnoses amongst young gay men at an all time high it is more important than ever same-sex relationships are taught in all schools in a respectful and supportive way.

“Behaviour learned at a young age stays with people, so it is important young gay men get the right information early on and are encouraged to practise safer sex.”

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