A senior British cleric has defended his attack on government plans to legalise same sex marriage.

Cardinal Keith O'Brien, the leader of the Catholic Church in Scotland, had described the plans as "grotesque" and said they would "shame the United Kingdom" in an article in the Telegraph.

He told the Today programme's John Humphrys that likening gay marriage to slavery is "a very good example" of what could follow on from the change in the law.

Same sex marriage "is not marriage", he maintained, which is defined by the United Nations Declaration of Human Rights as a relationship between a man and a woman. Countries which already support same sex marriage are "violating human rights".

"It's time to call a halt to what you might call progress", he said, saying that same sex marriage would lead to society "degenerating even further... into immorality".

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