A federal advisory board on test-tube creation of human life split yesterday over whether to permit such creation in the laboratory unless the resulting embryo is later implanted in a mother.

At the same time, the board may soon be willing to endorse such efforts as ethical if there is implantation so the embryo can grow.

The argument erupted as the Department of Health, Education and Welfare's eight-month-old Ethics Advisory Board, named to study the ethics of such efforts, opened its first debate, after public hearings.

Rev. Richard McCormick of Georgetown University, one of the nation's leading Catholic moral theologians, opened the argument against allowing creation of life simply for study.

He stood fast as doctors and scientists on the board argued that such study might be needed to assure the prospective parents that test-tube conception will be safe, with a good chance of producing a normal baby.

An embryo is created in a laboratory by joining sperm with an ovum -- a feat now performed many times, with two successful pregnancies to date, by British obstetrician Patrick Steptoe and a Cambridge University physiologist, Dr. Robert Edwards.

Scientists on the board seemed to agree that an embryo should not be kept alive for study for more than a few weeks. An embryo develops a heartbeat and human characteristics at three to four weeks of age.

But McCormick, a professor of Christian ethics at Georgetown's Center for Bioethics, said a laboratory embryo, at the first second of the joining of sperm and egg, becomes "life."

"When we have doubts about the claim that life makes on us. we must give life the benefit," he said.

He was willing to recommend that the federal government permit research on such living embryos, he said, but the government should not fund it, since "many of its citizens" would find this "morally repugnant."

Dr. Sissela Bok, a Harvard University medical ethicist, agreed, but on different grounds. She said implantation of test-tube embroys could be controlled to prevent abuses, but research on embroys might be a "first step" towar dugly and uncontrollablt applications, such a sjoining human and animal ova and sperm.

"I'd like to think we're capable of drawing lines," countered Dr. Robert Murray, a Howard University geneticist. "I think that risk is worth taking."

Research on embryos might lead to knowledge of infant development that might help prevent birth defects, Murray and others argued.

The board said that no matter what it recommends, U.S. doctors and scientists will be free to do whatever research they please, as long as they use nonfederal funds and facilities, and their studies are approved by their institutions' ethical review bodies.

Murray and other scientists on the board said that the heads of institutions with federal funding fear starting programs that the government brands as out-of-bounds.

There is currently a moratorium on all HEW-funded test-tube baby research except in animals. Only a team at the Eastern Virginia Medical School in Norfolk has said firmly it will continue work on humans with private funds.

HEW Secretary Joseph A. Califano Jr. named the 13-member board in May and asked it to help him decide what kind of research and applications HEW should fund.