The head of the Catholic Church in England and Wales, the Archbishop of Westminister, Cardinal Cormac Murphy O’Connor, has accused the Labour Government of imposing “a new morality”.

He was responding to the news that the Government was not prepared to give Catholic adoption agencies an opt out from new equality legislation which requires them to treat homosexual couples as prospective adoptive parents.

Instead of an exemption, Catholic agencies are to be given 20 months to adjust to the new rules. In practice this means they will close down at the end of this period.

Prime Minister Tony Blair said that the new arrangement was “a sensible compromise”, adding that there was “no room for discrimination” in British society.

However Cardinal Murphy O’Connor said that the decision was “very disappointing” and accused the Government of creating legislation which risked altering the moral framework of society.

“Some legislation, however well intended, in fact does create a new kind of morality, a new kind of norm – as this does,” he added.

“It does seem to me we are having a new norm for what marriage is, because I think normally children should be brought up by a father and a mother and I think that we hold that that is extremely important.

He went on to point out that the new law risked forcing religious people out of public life.

“Here the Catholic Church and its adoption services are wishing to act according to its principles and conscience and the government is saying: ‘No, we won’t allow you to … you have no space, you have no place in the public life of this country.’ he said.

“Now that seems to me to be just one step and there will be further ones.”

Cardinal Murphy O’Connor had appealed for an opt out in a letter to the Prime Minister and the rest of the Cabinet last week, saying that Catholic agencies would have no option but to close if they were forced to operate against Catholic teaching and their conscience.

Reports had suggested that Mr Blair was considering such an opt out, and that Communities Secretary Ruth Kelly, a practicing Catholic, backed the idea. However there was strong opposition to any exemption clause from most Cabinet ministers, with Education Secretary Alan Johnson, Northern Ireland Secretary Peter Hain and the Secretary of State for Constitutional Affairs, Lord Falconer among the strongest opponents of an opt out.

The Catholic Church’s stance was backed by the head of the Church of England, Archbishop of Canterbury Rowan Williams and The Muslim Council of Britain.

Conservative David Davis, the Shadow Home Secretary, also said that he would support an opt out for Church adoption agencies, although he stressed he was speaking personally and not for his party.

However, the leader of the Conservative Party, David Cameron, came out in favour of the legislation, and opposed the idea of an exemption.

A vote on the new proposal is expected next month. Mps who feel that the 20 months is an inadequate compromise will not be able to table amendments, and will only be able to accept or reject the proposal.