CARDINAL Keith O'Brien has launched a fresh attack on gay marriage, describing it as an "aberration" that would degenerate British society further into "immorality".

The UK Government, which is to launch a consultation on civil same-sex marriages later this month, responded to the remarks from the head of the Roman Catholic Church in Scotland by making clear David Cameron remained fully committed to equality.

However, while a spokesman for the PM noted the timetable set out would "allow legal changes to be made before the end of this parliament" in May 2015, he conspicuously failed to give a commitment that would happen.

The Scottish Government has already completed a consultation and received more than 50,000 responses.Its initial view was that gay marriage "should be introduced but believes faith groups and their celebrants should not be obliged to solemnise same-sex marriages", adding: "If, as a result of the consultation, the Government decides to legislate, there will be a further consultation on a draft bill. A finalised bill could then be introduced into the Scottish Parliament in 2013."

This throws up the prospect that Holyrood could legislate on the issue before Westminster and might mean the first major political battle over gay marriage could confront First Minister Alex Salmond rather than Mr Cameron.

Civil partnerships were introduced in 2005 to give homosexual couples the same legal rights as married couples but the law does not allow such unions to be referred to as marriages.

At the weekend, the cardinal argued ministers were trying to redefine marriage, which would "shame the United Kingdom in the eyes of the world".

Yesterday, the cardinal denied he was using inflammatory language, insisting he was simply handing on the teaching of the Christian church.

Margot James, the first openly lesbian Conservative MP, accused him of "scaremongering" and described his remarks as "completely unacceptable". Yet fellow Tory Peter Bone questioned where the issue of gay marriage had come from as it had not been in any party manifesto.