Schools will be forced to promote same-sex marriage to their pupils if the law is extended to include same gender couple unions, a senior lawyer has claimed.
Parents with traditional and religious views who oppose the union will be "hard-pressed" to remove their children from the classes, Aidan O'Neill QC has said.
"The extension of marriage to same sex couples is not one currently required under and in terms of the European Convention of Human Rights," he states.
"But if this is done, the case law of the European Court of Human Rights makes it clear that parents who insist on no marriage without committed and faithful heterosexual sex – will be hard-pressed to rely upon their Convention rights as parents to ensure education and teaching by the state of their children in conformity with their own religious and philosophical convictions."
The lawyer, who provided his opinion at the request of Scotland's Catholic Church, adds it will also be difficult for parents to excuse their children from attending sex education classes where this view is taught.
"Scottish Ministers and local education authorities have obligation to have "due regard" to the need to tackle prejudice and promote understanding in relation to matters of different sexual orientation.
"This duty applies regardless of whether marriage be opened to same sex couples."
Although O'Neill was commenting with regard to Scottish law, he indicated the same could apply to England.
Leader of the Scottish Catholic Church, Cardinal Keith O'Brien, said he would "urge" the Scottish government not to make promises they could not fulfil.
Ministers had previously assured teachers would not be required to include gay marriage in their lessons. O'Brien called the promises "hollow", saying: "It is clear that Scotland's schools will be banned from promoting a traditional understanding of marriage if same-sex marriage becomes law."
Andrea Williams, CEO of Christian Concern expressed her fears teachers would lose their jobs if they did not want to promote same-sex unions.
"Parents have the right to raise their children in accordance with their own religious values; yet if same-sex marriage is introduced and promoted in schools, that right will be undermined," she said
But Elly Barnes, LSBF schools campaigner, said:
"No diverse group can override another in terms of human rights, we all have the right to be treated fairly and equally as stated by the Equality Act 2010. This law is supported by our ‘Equal Opportunities’, ‘Sex and relationship’ policies and by our School Codes which are followed by all in our school communities to include staff, students, support staff and governors. If you believe in equality, which schools do and promote, then you believe in marriage for all. Young people have learnt through our school system not to discriminate, they are not born homophobic, racist, sexist..these are the negatives that outside influences ‘force’ upon them."
A Scottish Executive spokesman said ministers would listen to all views and no final decision has been reached, the Daily Telegraph reported.