The Vatican joined leading Muslim clerics and Jewish rabbis Saturday in denouncing as immoral, "brutal" and unnatural the claim that a cloned baby had been born.
Political leaders, meanwhile, stepped up calls for a global ban on human cloning.
The reaction came a day after a cloning company whose leader believes space aliens launched life on Earth announced that a baby girl, nicknamed "Eve," had been born as a clone of her mother.
Clonaid chief executive Brigitte Boisselier, a 46-year-old chemist with two doctoral degrees but no background in cloning, made the announcement of a cloned baby girl Friday at a press conference in Hollywood, Florida.
Clonaid was founded by the Raelian sect, which describes its "scientific creation" theology as an alternative to both Darwinian evolution and the creation dogma of some religions. The sect's leader, Rael, claims life on earth was created by extraterrestrials through genetic engineering.
A Vatican statement Saturday noted that the announcement came with no scientific proof and that it "has already given rise to the skepticism and moral condemnation of a great part of the international scientific community."
But "the announcement in itself is an expression of a brutal mentality, devoid of any ethical and human consideration," said the statement from papal spokesman Joaquin Navarro-Valls.
The Vatican has condemned any cloning of human embryos, saying the destruction of extra embryos in the process can in no way justify the procedure. Vatican teaching holds that life begins at conception.
Pope John Paul II himself has criticized any scientific experiment that threatens the dignity of a human life, including using human embryos for stem cell research.
In the Muslim world, clerics said cloning humans disrupted natural law and would create a "chaotic" future for humanity.
"Science must be regulated by firm laws to preserve humanity and its dignity," said Ali Abu el-Hassan, a cleric from Egypt's al-Azhar University, the top religious institution in the Muslim Sunni world.
Separately, a senior Saudi cleric, Ayed bin Ahmad al-Qurani, drew a distinction between human cloning and cloning of plants or animals, which he said could serve humanity.
Human cloning is wrong "because it will cause an imbalance in the human nature God has created," and it would lead to the spread of unknown diseases, he said. In addition, it could replace marriage for the sake of reproduction through one gender without the need for the other, which is "sinful, sinful, sinful," he said.
In Jerusalem, Israel's Chief Rabbi Israel Meir Lau said that in principle, Judaism favors technological developments and medical progress that can help save a life or solve infertility problems, but rejects the artificial creation of life.
"The moment medical science tries to take upon itself duties and areas which are not its responsibility such as shortening life, cloning, or creating life in an unnatural way we must set down borders in order not to harm the basic belief that there is a creator of the universe in whose hands life and death are placed," a statement from Lau's office said.
Several countries have already banned human cloning, including Germany and Britain. Others have legislation pending that would ban it or restrict it, such as Sweden, where the government is drafting legislation that would ban reproductive cloning but allow "therapeutic" cloning.
The United States has no specific law against human cloning. But the U.S. Food and Drug Administration, which regulates human experiments, says its regulations forbid human cloning without prior agency permission, and it has launched an investigation into whether Clonaid illegally performed any of the work on U.S. soil.
The United States has proposed a U.N. treaty banning all human cloning. France and Germany have proposed an alternative which would ban only cloning to produce babies, leaving the question of cloning for research and medical experiments for future consideration.
On Friday, French President Jacques Chirac vigorously condemned the announced birth and repeated calls for a worldwide ban on attempts to clone humans, which he said was "contrary to the dignity of man."
At the United Nations, a spokesman for Secretary-General Kofi Annan said the organization was waiting for scientific proof. "In any case, no one should expect the secretary-general to send flowers," the spokesman said.