Abortion leads to Nazi-style birth control and lets the strong decide the fate of the weak, Cardinal Cormac Murphy O'Connor has warned.
Britain is already on the road to Nazi-style policies, says the cardinal
The head of the Catholic Church in England and Wales wrote: "That way lies eugenics, and we know from German history where that leads."
He denounced "embryo selection on the basis of gender and genes".
Pro-choice campaigners said they were disappointed he had attacked "women's right to safe legal abortions".
The cardinal claimed human beings were made "instruments of other human beings", in the Sunday Telegraph article.
Britain was already on the road to Nazi-style eugenic - or selective breeding - policies, he argued.
"For what else is the termination of six million lives in the womb since the Abortion Act was introduced, and embryo selection on the basis of gender and genes?"
Cardinal Murphy O' Connor also said in an interview with Baroness Shirley Williams for the GMTV Sunday programme that it was "legitimate" for Catholics to discuss issues surrounding abortion.
But he insisted that he was not saying Catholics should vote for any one political party.
Pro-choice group Abortion Rights said: "We don't think political and religious leaders should play political football with women's lives.
"Most political leaders made it very clear in the last week that abortion should not be used as a political issue in the run up to the general election.
"This would risk a re-run of US election last November which made abortion, gay rights and stem cell research central to the debate in place of more pressing national and international concerns."
She said 76% of the public supported women's right to choose, and called for more widespread access to emergency contraception and sex education.
Meanwhile, another British Catholic leader has called on the electorate to ask questions about prospective MPs' views on "life issues" in the run-up to the General Election.
In his Easter message, the Archbishop of Birmingham, the Most Reverend Vincent Nichols, said voters should not only be sure of what they believed, but make "clearer demands" of elected representatives.
"No human being is simply a cog in a machine, a means to an end, a possession or a plaything. Human life is sacred," he said.