The Scottish Catholic Education Service has called for teachers to be free to teach their pupils that “marriage is uniquely a relationship between a man and a woman”.

The Scottish government is currently updating guidance on the conduct of sex and relationship education in Scottish schools.

The group’s director Michael McGrath made the claim in an article for the Scotsman.

He wrote: “When this revised guidance does see the light of day, I expect it to be unambiguous in its proclamation of same-sex marriage as a legal institution which extends the same legal rights as have been enjoyed traditionally by heterosexual married couples.

“However, I also hope that it will be fair in its consideration of those who believe that marriage is uniquely a relationship between a man and a woman.

“That consideration should extend to respecting the freedom of religious belief and expression of those who might be charged with teaching children and young people about marriage.

“Certainly in Scotland’s denominational schools, existing guidance enables teachers to follow guidance issued by the Catholic Church in the teaching of religious and moral issues (were this not to be the case, a school could not be recognised as “Catholic”).

“During the consultation phase of the new legislation, Scottish Government ministers gave assurances that this arrangement would continue to be honoured. So I expect to see these assurances reflected in its revised guidance.

Earlier this year, Scotland’s largest health board has warned the Scottish Government against allowing teachers and students to opt out of lessons on equal marriage and same-sex relationships.

NHS Greater Glasgow and Clyde is opposed to any regulations that would allow teachers or pupils to opt out on the grounds of “conscience”.