MSPs scrutinising the impact of the Scottish Government’s Marriage and Civil Partnership Bill have been told that parents should have the right to withdraw children from classes where same-sex marriage is discussed.

The demand was issued by the Family Education Trust, which says it has researched the “causes and consequences of family breakdown” for more than 40 years, the Ayrshire Post reports.

Michael Calwell, spokesman for the socially conservative group, said: “We need first of all what you might call a statutory obligation to inform parents if any teaching about marriage which conflicts with their view is raised in the classroom.

“The second thing would be the right to withdraw from that, and the third thing would be a positive obligation of the state to actually provide them with education that does conform with their understanding of the vital, pre-political if you like, nature and purpose of marriage.”

The Family Education Trust’s statement was presented to MSPs on Holyrood’s Equal Opportunities Committee. The Committee is responsible for scrutinising the Marriage and Civil Partnership (Scotland) Bill, and is hearing from a wide range of stakeholders before making recommendations to the Scottish Parliament on whether the bill should proceed and in what form.

Other groups represented at the hearing included Stonewall, the Scottish Catholic Education Service and teachers’ union the Educational Institute of Scotland.

Mr Calwell also argued that growing numbers of immigrants with strong views against same-sex marriage could pose problems should equal marriage be introduced.

“You have to be mindful of the way Scotland is changing, particularly with the inflow of people from very strong pro-family, pro-marriage cultures,” he said.

“This is actually visibly the case, particularly where I live.”

He continued to say: “We’re going to become increasingly reliant on people from these demographic backgrounds in Scottish society as our natural population, if you like, declines.

“If we don’t make provisions in this law to protect parents who want and need their children to have an understanding of marriage which is constant with their views we could end up with a lot of problems in classrooms, particularly with parents taking local education authorities to court.”

Mr Calwell went on to argue that same-sex marriage as set out in the bill is a conflicting and radical invention by a small political class.

The Marriage and Civil Partnerships (Scotland) Bill was introduced into the Scottish Parliament in June, before entering the committee stage in early September.

Support for equal marriage is high in the Scottish Parliament. Over two-thirds of MSPs have signed the Equality Network’s “Equal Marriage Pledge” committing themselves to voting in favour of same-sex marriage. Signatories include First Minister Alex Salmond, all Cabinet Ministers, and the leaders of all four parliamentary opposition parties. Whilst 89 MSPs have now said they will vote in favour, just 10 are publicly opposed.

Various Scottish public figures have spoken out in favour of equal marriage as part of the Equality Network’s It’s Time campaign. The most recent star to back the campaign was Lord of the Rings star Billy Boyd.