SAN FRANCISCO (AP) -- Stanford University reignited the debate over the use of stem cells when a top scientist said the school intended to experiment with nuclear transfer technology, an effort many consider to be cloning.

"Our avowed goal is to advance science," said Stanford medical professor Dr. Irving Weissman, who will direct the school's stem cell effort. "For any group to stay out of the action and wait for someone else to do it because of political reasons is wrong."

Weissman said he intends to recruit the "very best" experts in nuclear transfer research to Stanford. He said there are five or six acknowledged leaders in the world and he wants "to put them on notice that we are after them."

Weissman -- and Stanford -- emphatically denied that the project involves cloning embryos. He said that the university's work would involve taking DNA from diseased adult human cells and transferring them into eggs, then growing them in the lab for a few days.

"Creating human stem cell lines is not equivalent to reproductive cloning," the school said in a statement released at a news conference Tuesday night.

"The first step in the process of creating a stem cell line involves transferring the nucleus from a cell to an egg and allowing the egg to divide. This is the same first step as in reproductive cloning. However, in creating a stem cell line, cells are removed from the developing cluster. These cells can go on to form many types of tissue, but cannot on their own develop into a human."

Many other researchers say this is a distinction without a difference -- that this kind of nuclear transfer -- which would create an exact genetic replica of the adult cell donor if allowed to grow -- is in fact cloning.

The American Association of Medical Colleges, of which Stanford is a member, defines it this way:

"Somatic Cell Nuclear Transfer (SCNT) or therapeutic cloning involves removing the nucleus of an unfertilized egg cell, replacing it with the material from the nucleus of a `somatic cell' (a skin, heart, or nerve cell, for example), and stimulating this cell to begin dividing."

But similar research has already been done at the University of California, San Francisco, which ultimately closed down its program as its lead researcher was preparing to leave for England, where stem cell research is more accepted. It's also been done at Advanced Cell Technology in Worcester, Mass., which was roundly criticized after announcing preliminary results from its research.

Scientists believe that embryonic stem cells, which are created in the first days of pregnancy and develop into all the cells that comprise a human body, can be used to treat many illnesses.

Embryos must be destroyed to harvest the stem cells, and some anti-abortion activists and others oppose the research.

Ronald Green, the chairman of Advanced Cell's ethics advisory committee and a religion professor at Dartmouth University, applauded Stanford's announcement, but said "cloning" is in fact the mostly widely accepted term for what Weissman's team plans to do.

"We've been struggling with names for this technology -- I've favored 'therapeutic cloning,"' Green said. Other leading ethicists call it "biomedical cloning" and draw a distinction between it and "reproductive cloning."

While "cloning" suggests the production of a baby, and that's not Stanford's intent, "you are creating something that some view as an embryo," Green said, adding: "Almost any terminology is inadequate to explain the complex science."

Nobel laureate and Stanford professor Paul Berg, when asked at the news conference if nuclear transfer and cloning were the same, he had a two-word response: "It is."

He added. "We use the word cloning in science as a term to describe the production of many copies of a starting material."

Stanford's stem cell work will be part of the new Institute for Cancer/Stem Cell Biology and Medicine, launched with a $12 million donation. Much of the institute's research will be geared to treating cancer. Any stem cells created will be shared with outside researchers, many of whom complain of inadequate access to currently available stem cell lines.

Weissman, an outspoken stem cell research proponent, was named institute director.

Weissman, serving as chairman of a National Academy of Sciences panel, testified before the U.S. Senate this year in favor of nuclear transfer as a way of creating new lines of stem cells.

Last year, President Bush limited federal funding to stem cell lines created before Aug. 9, 2001. Of those 78 stem cell colonies worldwide that the Bush administration has said are eligible for federally funded research, only about a dozen are in good enough shape to use in experiments.

Even fewer -- perhaps four lines -- are being routinely shared and sent to other researchers interested in breaking into the field.

Copyright 2002 The Associated Press. All rights reserved.