Ministers fear forthcoming legislation will be hijacked by MPs wanting to cut the time limit on abortions.
Changes to the law on fertilisation and embryology could set the stage for a parliamentary showdown on abortion, according to Health Minister Caroline Flint.
Many social conservatives feel that the current 24-week period is too long while some Tory MPs have signalled their support for a move to reduce it.
In a memo to Prime Minister Tony Blair, Ms Flint warns that her forthcoming draft Human Tissue and Embryos Bill could be used to raise the subject.
The document, leaked to The Sunday Telegraph, says: "There is a possibility that some members may wish to use the opportunity presented by the draft Bill to discuss wider issues dealt with by the original legislation...and related topics of interest notably abortion (under the Abortion Act 1967).
"Provisional advice from the House authorities suggests that these topics could not simply be ruled out as a matter of scope."
Conservative MP Ann Widdecombe promised that the opportunity would not be missed. "We will go for it and we will go hard and fast on it," she told The Sunday Telegraph. "I think it would be a major campaign and I would absolutely be there."
Fellow Tory backbencher Ann Winterton said it was time for the issue to be revisited. "What we want to see is a wide ranging debate, because science has changed dramatically in the last 40 years abortion it hasn't been debated properly since then," she said.
Former Tory leader Michael Howard also signalled his support for a challenge.
Mr Howard, who called for a cut during the 2005 general election, said: "I haven't changed my views, I do believe the limits should be reduced to 20 weeks and I would vote for that."
