Catholic Ministers of Parliament could revolt against Labor Party leader Prime Minister Gordon Brown over a bill on embryo fertilization and research, the Telegraph reports.

The Human Fertilization and Embryology Bill will allow the creation of human-animal hybrid embryos containing both human and animal DNA and will loosen restrictions on in-vitro fertilization treatments for single women and homosexual couples.

Transport Secretary Ruth Kelly, Defense Secretary Des Browne and Welsh Secretary Paul Murphy are devout Catholics, who have threatened to resist the bill because of ethical and religious objections.  The Archbishop of Westminster Cardinal Cormac Murphy-O’Connor has criticized the bill and has called for “flexibility” in parliamentary deliberations.

Prime Minister Brown had considered permitting a free vote on the bill, which otherwise must be supported by all party members.  Brown decided such a move would anger other MPs who had previously stayed loyal to the government.

The opposition of such high-ranking Cabinet members has renewed the controversy.  A possible option is to allow Catholic legislators to abstain from the vote, though some Catholics have pressed for the liberty to vote against the bill or amend it to remove some measures.

According to The Telegraph, a government source said, "This is a vital Bill and the Prime Minister has taken a close interest.

"That means we have to get it through. But when you are talking about people's religious beliefs, particularly among Cabinet ministers, then it creates problems."

The Conservative Party leader David Cameron has allowed a free vote to his party's Ministers of Parliament.

The recent promotion of Paul Murphy to Welsh Secretary has also heightened the controversy, as Murphy is considered the most devout Catholic in the Cabinet.  Ruth Kelly, the Transport Secretary, has also been the focus of controversy. Kelly reportedly argued with the government last year over government mandates that Catholic adoption agencies place children with homosexual couples.

Mr. Brown and Health Secretary Alan Johnson believe the Bill to be vital in the search for cures for syndromes such as motor neuron disease and cystic fibrosis.

The Bill, which has already been delayed in an attempt to reach a compromise, will be voted on in the next two months.