The Government was accused today of offering faith schools an "opt-out" on new national requirements on the teaching of issues like homosexual equality and contraception in sex education lessons.
Provisions in the Children, Schools and Families Bill, which completes its passage through the House of Commons today, will require state schools in England and Wales to teach pupils about contraception and the importance of stable relationships including civil partnerships and forbid the promotion of homophobia.
But an amendment tabled by Children's Secretary Ed Balls will allow faith schools to teach such issues in a way which reflects their religious character.
Liberal Democrat schools spokesman David Laws accused ministers of being in a "terrific muddle" over the issue, arguing that this last-minute change "completely undermines the objectives of this part of the Bill".
The amendment would allow faith schools to dodge requirements to promote equality and respect for diversity in a way which some people would consider intolerant, he said.
Mr Laws told the BBC Radio 4 Today programme: "The issue is, in the 21st century, are we going to have a school system which is going to be tolerant of intolerance in the name of religious freedom?
"Or should we say in the 21st century that it is right that all state-funded schools should be teaching tolerance and respect for diversity?
"After all, there are already opt-outs for parents and there is already the wider obligation to teach in relation to the religious and culture background of pupils."
Rabbi Dr Jonathan Romain, of the Accord Coalition which campaigns on education issues, told Today: "It is precisely because this is such an enlightened and progressive Bill that we are astonished and saddened by the fact that (Mr Balls) has now chosen to amend his own Bill and to effectively give faith schools an opt-out.
"If a school doesn't approve of contraception or abortion or homosexuality, then it can give that message or it can omit certain facts. We know there are some faith schools which take a very negative view.
"I value religion - not just my own but the faith of others - but I value even more that children should have exactly what Ed Balls intended: a balanced and accurate education."
But Mr Balls insisted that his Bill had always included a recognition that faith schools should be able to teach sex relationship education "within the context and ethos of their faith".
"All the amendment does is clarify on the face of the Bill the fact of that status quo," he told Today.
Mr Balls said the Bill was "a major step forward" in requiring all schools not only to teach children about the biology of sex but also about relationships, and in lowering the maximum age for parents to keep their children out of sex education classes from 19 to 15.
He said: "There is no watering down of what is actually an overdue change. There is no opt-out for any faith school from teaching the full, broad, balanced curriculum on sex and relationship education and that is a huge step forward."
And he added: "Every school will have to teach the full curriculum in a balanced way that respects equality and is not discriminatory, but of course what we are saying is they can explain the views of their faith.
"Catholic schools can say to their pupils that, as a religion, we believe contraception is wrong, but what they can't do is therefore say they are not going to teach about contraception."