The Catholic Church in Scotland has criticised new adoption laws that will give unmarried couples, including gay couples, in Scotland adoption rights.

Under current law, only married or single people may adopt while gay and unmarried couples may raise a child jointly but with only one of them regarded as the legal parent. This will now change so that gay and unmarried couples have the same adoption rights as married or single people.

The change sparked a furious debate at the Scottish Parliament yesterday as Minister for Education and Young People, Peter Peacock, was forced to go on the defensive.

Peacock fought off fierce opposition to the changes, insisting they would result in even more children being placed in new homes.

He stressed that marriage was still widely recognised as the best environment in which to raise a child but added, "There is, more than at any other time in modern history, a wide diversity of family arrangements in Scotland".

The Adoption and Children (Scotland) Bill does not give any couple an uncontested "right" to adopt a child as applications will still be considered case by case before having to obtain the approval of a court.

Calling herself "the only openly gay parent in this chamber", Liberal Democrat MSP Margaret Smith, defended the new adoption rights for same-sex couples.

"I have brought up children on my own, and as part of a couple, and I have to say it's easier as part of a couple," she said.

The Roman Catholic Church in Scotland has long led a campaign against changes in the adoption laws, advocating instead the stability of raising children within a traditional marriage framework.

Bishop of Motherwell, Joseph Devine, urged MSPs to vote against the move after the Bishops' Conference of Scotland described it as "irresponsible".

Just last week Bishop Devine wrote a letter to MSPs in which he said the "distressing legislation" was a "violation of family life". He reacted to the changes in the law by vowing that the Catholic Church would fight on.

"The result is very worrying, especially for children who will be caught up in these disturbing adoption processes," he said.

"But there are another two stages of the bill yet to go through Parliament, so this file is far from closed. The Church is not going to stay quiet."

A number of MSPs also voiced their opposition to the change in adoption law.

Roseanna Cunningham of the SNP said, "I can't see how overturning tens of thousands of years of nature's design moves us forward."

Joseph Devine, the Bishop of Motherwell, who Dr Gordon Macdonald, parliamentary officer for Christian group Care, said his organisation was also against the changes.