The Irish Catholic think tank the Iona Institute, has released a video and a document that argues that gay couples should be banned from marrying “for the sake of the children.” It also argues that same-sex marriage could lead to children not being brought up by their parents.

In a document, the organisation says: “The marriage of a man and a woman has a special position in Irish society and in the Irish Constitution.

“It is the only form of human relationship that has the status of a social institution. This special status is now deemed by some people to be inherently discriminatory in that it ‘discriminates’ against all other types of families, including same-sex couples.”

In the video, the group says that gay couples should be entitled to legal recongition of their relationships, but not marriage.

In the paper, the institute appears to argue that allowing same-sex couples to marry might lead to children not having the right to be raised by their parents: “Those who claim that same-sex couples and married opposite-sex couples should be treated identically must demonstrate that there is no advantage to children in encouraging men and women to marry. They must also demonstrate that children have no right to be raised by their own mother and father, even as a matter of first principle.

“Only after demonstrating that there is no relevant difference between opposite-sex couples and
same-sex couples, especially from the point of view of children, and that the right to a mother and father where possible does not exist, can same-sex marriage be justified.

“It is also out-of-bounds to denounce as ‘bigots’ and ‘homophobes’ those who have perfectly rational, evidence-based reasons for believing that there is a relevant difference between opposite and same-sex couples. No such denunciation is aimed at those who believe there is good reason to treat marriage and cohabitation differently.”

Last month, the Irish deputy prime minister (Tánaiste) Eamon Gilmore said he would like to see a referendum on same-sex marriage “as soon as possible”.

Mr Gilmore said his own view was that the “time has come” for Ireland to introduce marriage rights for gay couples. “I don’t believe we should postpone what is a human right.”

In October, Ireland’s former president Mary McAleese announced her support for equal marriage.

Same-sex civil partnerships became legal in the country in February 2011.