Alistair Burt, a junior social security minister, said: 'The decline of marriage as an institution and the increase in cohabitation are to be regretted if it results in more separations and in more relationships breaking up.'
Labour attacked his comments as a return to the 'tarnished old back-to-basics campaign', which rebounded on the Prime Minister after a string of Tory sex scandals.
Mr Burt made his comments to the Royal Scottish Society for Prevention of Cruelty to Children, in Glasgow.
Mr Burt, the Under-Secretary of State responsible for the much- criticised Child Support Agency, cited the British Household Panel Survey 1991-92. One finding was that cohabiting couples were more than four times more likely to split up than married couples.