A CATHOLIC bishop has sparked controversy by suggesting that, if the Scottish Government truly believed in equality, it could extend legislation on same-sex marriage to encompass bigamy and even incest.

Bishop Hugh Gilbert of Aberdeen asked why equality did not extend to "nieces who genuinely, truly love their uncles" and why men could not have two wives, adding such scenarios were not freaks of nature but might in fact occur in Scottish parishes.

Equality Network, the pro-gay marriage group, described Bishop Gilbert's remarks as offensive and unwarranted.

Senior sources within the Church claim Scotland's bishops are about to pull out of discussions with ministers over same-sex marriage, claiming the recent consultation was "a sham" and that the Government had already made its mind up to push ahead with legislation.

In an interview with the Scottish Catholic Observer (SCO), Bishop Gilbert, the first to be appointed in Scotland by Pope Benedict, said: "You can't have a meal without food and you don't have marriage without a man and a woman. This isn't just social convention. It's not something any Government can change. It's a fact of life.

"The truth is that a Government can pass any legislation it likes, it can legislate to say everything with four legs is a table, even when it's a dog and not a horse, but that won't make it so. Why is it all right for a man to marry another man, but not all right for him to marry two women? If we really want equality, why does that equality not extend to nieces who genuinely, truly love their uncles? And, if you say that such things don't happen, that they are mere freaks of nature, extreme examples dreamed up for the sake of argument, I say you need to spend more time in the parish."

He added: "As Bishop of Aberdeen, I know there are gay people among the community of the Church. I promise I will always respect and love them and uphold them in their relationship with the God who loves them. But I won't marry them. It just can't be done."

A senior Church source also told the SCO: "The Scottish Government said it was committed to consult on the redefinition of marriage, but it has not listened to the result of that consultation. Now it may or may not engage in a second consultation and it is already committed to legislate. At this stage we have to wonder if there is any point to engaging further."

A leading figure in Scotland's Muslim community backed the Catholic stance on continuing dialogue on gay marriage but said he would need to consult with the wider Islamic community before deciding if they would pull out of the talks.

In its timetable for a Bill on same-sex marriage, the Scottish Government included further consultation with the Catholic Church and Church of Scotland to consider any additional safeguards for freedom of religion.

Tim Hopkins, director of Equality Network, said: "We are very disappointed the Bishop of Aberdeen should choose to compare same-sex marriage to polygamy and incest. That is offensive and uncalled for. Let's have a respectful discussion about the Government's proposals, rather than complaints about something imagined that forms no part of those proposals.

"It is ironic that having complained, wrongly, they would be forced to conduct or approve of same-sex marriages, the Church is now refusing to discuss with the Government the very protections that will ensure their continued freedom to object and opt out."

A Scottish Government spokesman said: "We are committed to protecting freedom of speech and freedom of religion. In taking forward this legislation we will discuss the range of concerns with stakeholders, and what additional protections should be included. We encourage all stakeholders to participate."