Supporters of the embryos Bill are urging MPs to vote it through.

Supporters of the Government's controversial embryo research legislation were fighting back after an Easter weekend which has seen it condemned from pulpits up and down Britain.

A coalition of charities and support groups representing scientists, doctors and patients suffering from a wide range of serious conditions has written to every MP urging them to back the Human Fertilisation and Embryology Bill.

The letter, which cites "overwhelming support" for the bill among medical charities, came amid indications that Prime Minister Gordon Brown is seeking a compromise solution to avoid a split in his Cabinet.

Health Secretary Alan Johnson said that an "accommodation" would be reached with Labour MPs in order to avoid forcing them to vote against their conscience.

Unconfirmed reports suggest that this may involve allowing MPs such as the Catholic Cabinet members Ruth Kelly, Paul Murphy and Des Browne to abstain from voting on elements of the Bill, so long as this does not prevent its successful passage through the Commons.

Normally, a three-line whip would be imposed for a Government bill, and any ministers failing to support it would be expected to resign.

Church leaders, including the head of Roman Catholics in England and Wales, Cardinal Cormac Murphy-O'Connor, are urging Mr Brown to allow his MPs a free vote on what they regard as a matter of conscience, as Conservative leader David Cameron and the Liberal Democrats' Nick Clegg have done.

Scottish Cardinal Keith O'Brien said the bill would allow "grotesque procedures" which would "attack the sanctity and dignity of human life".

But fertility expert Lord Winston, a Labour peer, told the Daily Telegraph: "His statements are lying. They are misleading and I'm afraid that when the Church, for good motives, tells untruths, it brings discredit upon itself."

In a round of media interviews designed to ease pressure on the Government yesterday, Mr Johnson left no doubt that Mr Brown was considering an arrangement to avoid a clash with MPs, several of whom have publicly stated that they will rebel if a three-line whip is imposed.