CATHOLIC priests have been ordered to instruct parishioners to vote against MPs who support the proposed embryo research bill that allows experiments on human-animal hybrids.

Cardinal Keith O'Brien, leader of the Catholic church in Scotland, has issued directions to clergy to lead the campaign to block the human fertilisation and embryology bill from the pulpit.

All 500 parishes in Scotland will receive a letter asking them to lobby their local MPs and warn them that the church will work to unseat them at the next general election if they support the bill. The advice will be read out by priests during Sunday services.

O'Brien has claimed that the new measures, which will facilitate research into genetically inherited diseases such as Parkinson's and Alzheimer's, will amount to a “monstrous attack on human rights, human dignity and human life” that would lead to “experiments of Frankenstein proportion”.

Gordon Brown, who supports the legislation, has already bowed to pressure, offering Labour MPs free votes on the most controversial areas, but he expects them to back the full bill at the later stages.

The threat from the Catholic church means that several MPs, already worried about losing seats to a resurgent SNP, will be forced to choose between defying the prime minister or alienating Catholic voters.

A relatively small swing away from about 10 Scottish Labour MPs would be enough to oust them from the Commons. Casualties could include Nigel Griffiths, the Edinburgh South MP who is a close ally of the prime minister, Jim Murphy, the minister for Europe, and Anne McGuire, minister for the disabled.

O'Brien is encouraged by a poll published last week showing that two-thirds of people are opposed to the creation of hybrid embryos.

His letter to parishes states: “Sadly, many members of parliament do not seem concerned — or rather are in a certain ignorance of what is going to happen. Some have claimed that few of their constituents are interested in the subject.

“This means that Catholic MPs must act and vote with an informed conscience, always mindful of the teaching of the church on the dignity and sanctity of human life. It also means that as Catholic voters we too must act with an informed conscience when we next come to cast our vote at the ballot box — asking, ‘Did my MP reflect my concerns on this issue?'”

Cardinal Cormac MurphyO'Connor, leader of the Catholic church in England and Wales, has also sent out a pastoral message to Catholics south of the border urging them to put pressure on their MPs.

Faced with the prospect of ministerial resignations over the matter, Brown announced that MPs will be able to follow their consciences in a free vote on three areas of the legislation — including allowing scientists to create embryos with human DNA and animal cells.

However, he expects all Labour MPs to back the whole bill when it comes to the final Commons vote. That is thought to have satisfied Des Browne, the defence secretary and MP for Kilmarnock and Loudon.

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