Roman Catholic Church officials said the recently created first synthetic cell could be a positive development if correctly used, but warned scientists that only God can create life.
Vatican and Italian church officials were mostly cautious in their first reaction to the announcement from the United States that researchers had produced a living cell containing manmade DNA.
They warned scientists of the ethical responsibility of scientific progress and said the manner in which the innovation is applied in the future will be crucial.
"It's a great scientific discovery. Now we have to understand how it will be implemented in the future," Monsignor Rino Fisichella, the Vatican's top bioethics official, said.
"If we ascertain that it is for the good of all, of the environment and man in it, we'll keep the same judgment," he said.
"If, on the other hand, the use of this discovery should turn against the dignity of and respect for human life, then our judgment would change."
Mgr Fisichella, who heads Vatican's Pontifical Academy for Life, stressed there is no necessary clash between science and faith.
"We look at science with great interest. But we think above all about the meaning that must be given to life," Mgr Fisichella told state-run RAI television. "We can only reach the conclusion that we need God, the origin of life."
Catholic Church teaching holds that human life is God's gift, created through natural procreation between a man and woman.
The Vatican newspaper, L'Osservatore Romano, called the synthetic cell "an interesting result" but stressed that it "must have rules, like all the things that touch on the heart of life".
The paper said genetic engineering can do good but acts on "a very fragile terrain".
"It's all about combining courage with caution," it said.
The inventors said the world's first synthetic cell is more a re-creation of existing life - changing one simple type of bacterium into another - than a built-from-scratch kind.
But genome-mapping pioneer J. Craig Venter said his team's project paves the way for designing organisms that work differently from the way nature intended for a wide range of uses.
A top Italian cardinal, Angelo Bagnasco, said the invention is "further sign of intelligence, God's gift to understand creation and be able to better govern it," according to Apcom and Ansa news agencies.
"On the other hand, intelligence can never be without responsibility," said Cardinal Bagnasco, the head of the Italian bishops' conference. "Any form of intelligence and any scientific acquisition ... must always be measured against the ethical dimension, which has at its heart the true dignity of every person."
Another official with the Italian bishops' conference, Bishop Domenico Mogavero, expressed concern that scientists might be tempted to play God.
"Pretending to be God and parroting his power of creation is an enormous risk that can plunge men into a barbarity," the Bishop told newspaper La Stampa in an interview. Scientists "should never forget that there is only one creator: God".
"In the wrong hands, today's development can lead tomorrow to a devastating leap in the dark," said the Bishop, who heads the conference's legal affairs department.