Maria Miller, the culture secretary and minister for equalities has attempted to dampen fears that teachers could face action for telling children they oppose same-sex marriages.

Mrs Miller, speaking to BBC Radio 4’s Today programme ahead of the publication of the Marriage (Same-sex couples) Bill defended the government’s plans to introduce full gay equality.

“Look, teachers are able to and entitled to express their views about same-sex marriage and there’s no requirement at all for them to promote it but, obviously, we wouldn’t expect teachers to be offensive or discriminate in any way about anybody,” she said.

“I think it’s important to say that in the context of talking about religious belief, perhaps in a church school that, there are different views on these matters, that there are views that marriage is between a man and a woman, particularly when it comes to, say, the Church of England, the Catholic church or the Church in Wales.

“You think you always expect our teachers to teach in a balanced way and nothing’ changed in that respect, but, obviously, it’s important that children do know that there are different beliefs within different religious faiths.”

Schools currently have a duty to promote the institution of marriage as part of the national curriculum.

An aide to the education secretary, Michael Gove, himself one of the Parliamentary proposers of the bill, warned yesterday that the ultimate decision on what teachers can say might lie in Europe.

“We have had legal advice, the problem is that there is this inherent uncertainty about such matters,” an aide told the Daily Telegraph.

“These are all under the control of nine guys in Strasbourg, it is just fundamentally uncertain because Britain isn’t in control of this.”

The aide pointed to the case of Lillian Ladele, a civil registrar who refused to conduct same-sex civil partnerships and who lost a case at the the European Court of Human Rights earlier this month. Her job though was explicitly to conduct marriages and civil partnerships, not quite the same as a teacher, whose job it is to teach a variety of lessons, one or two of which would be about marriage.