US Catholic prelates fresh from a wrestle with House Speaker Nancy Pelosi over her abortion statement, have now turned their criticism to Democratic vice presidential nominee Joe Biden, who they say misrepresented church teaching on human life in a recent interview.

Cardinal Justin F Rigali and Bishop William E Lori, two prominent US Catholic leaders, said Tuesday that although Biden correctly stated that Catholic teaching says human life begins at conception, he was wrong to claim that the beginning of human life issue is a "personal and private" matter of religious faith.

The debate on when life begins is first a biological question and secondly a moral question, the Catholic leaders contend.

Embryology textbooks today, they say, confirm that new life begins at conception.

"The Catholic Church does not teach this as a matter of faith; it acknowledges it as a matter of objective fact," Rigali, chairman of the US Bishops' Committee on Pro-Life Activities, and Lori, chairman of the US Bishops Committee on Doctrine, said in a joint statement.

Regarding the moral question, the bishops said, the Catholic Church teaches that everyone deserves fundamental human rights.

"No human being should be treated as lacking human rights, and we have no business dividing humanity into those who are valuable enough to warrant protection and those who are not," they say. "This is not solely a Catholic teaching, but a principle of natural law accessible to all people of good will."

They continue: "Those who hold a narrower and more exclusionary view have the burden of explaining why we should divide humanity into those who have moral values and those who do not and why their particular choice of where to draw that line can be sustained in a pluralistic society."

Last week, House Speaker Pelosi agreed to meet with the archbishop of her hometown of San Francisco to discuss church teaching. She had come under a barrage of criticism from Catholic leaders after she said on "Meet the Press" that "doctors of the church" disagree on when life begins and that abortion continues to be a controversial issue among them.

But Catholic leaders say that Pelosi is mistaken and that the Church has held onto its anti-abortion stance since the first century.