Cardinals add voice to embryo row

The Archbishop of Westminster, Cardinal Cormac Murphy-O'Connor, urged Catholic MPs - who include three members of Mr Brown's Cabinet - to vote according to their convictions on the Human Fertilisation and Embryology Bill, which would allow the creation of human-animal hybrid embryos for medical research.

His intervention comes as the head of Scottish Catholics, Cardinal Keith O'Brien, prepares to deliver a scathing denunciation of the Bill in his Easter Sunday sermon.

Cardinal O'Brien will tell worshippers at St Mary's Cathedral in Edinburgh that the planned legislation amounts to a "monstrous attack on human rights, human dignity and human life" which will allow experiments of "Frankenstein proportion".

In a pre-recorded interview to be broadcast by Sky News on Sunday, Cardinal Murphy-O'Connor said: "I think Catholics in politics have got to act according to their Catholic convictions, so have other Christians, so have other politicians.

"Certainly, there are some aspects of this Bill on which I believe there ought to be a free vote, because Catholics and others will want to vote according to their conscience."

The churchmen's comments will heighten the pressure on Catholic members of Mr Brown's Cabinet: Transport Secretary Ruth Kelly, Wales Secretary Paul Murphy and Defence Secretary Des Browne.

Reports have suggested Ms Kelly and Mr Murphy are privately warning they will resign rather than back the Bill.

As Government legislation, a three-line whip would normally be imposed on all Labour MPs to vote for the Bill - as happened with the party's peers when it was introduced in the House of Lords. Any minister who failed to support it in a whipped vote would be expected to resign.

But Mr Brown has yet to make clear whether he will grant his MPs a free vote, as Conservative leader David Cameron and the Liberal Democrats' Nick Clegg have done. He told the Commons earlier this month that a decision would be taken "in due course".