Forcing older pupils to study religious education is an abuse of their human rights, a cross-party group of MPs and peers has said.
The Parliamentary joint committee on human rights said in a report that pupils aged 16 and over should be able to opt out of RE lessons.
Ministers have already conceded that older pupils should not be forced to take part in collective worship, a move which represents one of the biggest reforms of the laws governing religion in schools for more than 60 years.
Lord Adonis, the schools minister, said last month that the education and inspections Bill would be amended, giving pupils over 16 the right to withdraw themselves, a power previously extended only to their parents.
In its latest report on the Bill, the joint committee of peers and MPs, established to scrutinise legislation and ensure it does not contravene human rights, welcomed the reform but said it did not go far enough. They said that under article 9 of the European Convention on Human Rights, pupils should be able to "enjoy the right to freedom of thought, conscience and religion". "This is a right they enjoy in their own right, not a right belonging to their parents," the report said.
The report said that a "16-year-old who does not wish to receive religious instruction" could only be excused from RE lessons with the consent of parents, "who may not necessarily grant the request."
"In our view this would be likely to lead to a breach of the pupil's article 9 right to freedom of thought, conscience and religion," it said.
The recommendations have been welcomed by the National Secular Society, which has been pushing for a reform of the laws.
Keith Porteous Wood, its executive director, said: "It is sometimes difficult to escape the conclusion that with the DfES religion trumps all even, as in this case, human rights."
He said the society would continue to push for further reforms, including the abolition of compulsory RE for children of all ages.
"It is clear that government policy on RE and collective worship does not comply with the Human Rights Act," he said. "We don't just want a half-hearted amendment to current legislation."
Brian Gates, chairman of the RE Council for England and Wales, said the recommendation had been influenced by a "negative and exclusive" campaign orchestrated by the NSS. He said: "If, by pressing the opt-out clause, the committee thinks it is doing something positive for young people's need to make sense of religion in the contemporary world, it is deceiving itself.
"The committee would be better advised if it addressed the question of what provision is being made for all students aged 16-19, in respect of the opportunities they have to enrich the beliefs and values by which they are going to live their lives as British and global citizens."
Jack Lewars, 17, who attends King Edward VI grammar, Chelmsford, and sits on the executive council of the English Secondary Students' Association, said: "I appreciate learning about other cultures is important but I am pro-choice for students. RE should be made voluntary, but students should have enough information about it in advance so they can make an informed choice on whether to study it.
"Personally, I'm not entirely clear RE compromises your right to freedom of thought any more than compulsory lessons in any other subject."
But the joint committee's recommendations are likely to be resisted by churches and could make awkward reading for ministers who have sought to improve the standing of RE in schools.
It is not the first time the joint committee has criticised the education Bill.
A report released in May said proposed new powers allowing teachers to use "reasonable" force to stop pupils disrupting classes may constitute an abuse of their human rights. It also said plans to allow teachers to confiscate mobile phones could also be discriminatory.
RISE OF RE
RE is the fastest-growing subject at GCSE and A-level: nearly 60 per cent of pupils now take a full or short-course GCSE.
Teacher recruitment, boosted by a "golden hello" for new RE specialists, is up 40 per cent this year compared with 2005.
RE is compulsory for all pupils but is the only subject not included in the national curriculum. Syllabuses are drawn up by local committees of religious leaders and teachers, a process criticised in the past by Ofsted for producing inconsistencies. In 2004, the Government introduced a voluntary national framework for the subject in a bid to improve poor local syllabuses. Ministers have pledged more money to improve teacher training.