VATICAN CITY — A Vatican official on Saturday criticized a new method of making stem cells that does not require the destruction of embryos, calling it a "manipulation" that did not address the church's ethical concerns.

Monsignor Elio Sgreccia, the Vatican's top official on bioethical questions, said in an interview with Vatican Radio that the method of making stem cells devised by scientists at Advanced Cell Technology Inc. in Alameda, Calif., remains an in-vitro form of reproduction, which the church opposes.

"That, from a point of view that is not only Catholic, but from a point of view of bioethic reasons, is a negative factor," said Sgreccia, who heads the Vatican's Pontifical Academy for Life.

Church teaching holds that in-vitro fertilization is morally wrong because it replaces the conjugal union between husband and wife and often results in the destruction of embryos. Artificial insemination for married couples is allowable if it "facilitates" the sex act but does not replace it. The church condemns all forms of experimentation on human embryos.

Advanced Cell's method "doesn't solve the ethical problems," Sgreccia said.

The new method — described online Wednesday in the British journal Nature — works by taking an embryo at a very early stage of development and removing a single cell, which could then spawn an embryonic stem cell line. With only one cell removed, the rest of the embryo retains its full potential for development.

But Sgreccia said the new method does not address what he said was the fact that even the single cell removed in the new approach could theoretically grow into a full-fledged human.

The current method of creating stem cells involves the destruction of embryos after about five days of development, when they consist of about 100 cells.

Stem cells are important because of their potential to transform into any type of human tissue, perhaps leading to new treatments for a series of illnesses.

But the Vatican and President Bush, among others, have argued that the promise of stem cells should not be realized at the expense of human life, even in its most nascent stages.

Pope Benedict XVI said in February that embryos developed for in-vitro fertilization deserve the same right to life as fetuses, children and adults — and that that right extends to embryos even before they are transferred into a woman's womb.

Benedict's comments were significant because he specified that even an embryo in its earliest stages — when it is just a few cells — is just as much a human life as an older being.