The head of a Seoul fertility clinic associated with an embattled Korean stem cell researcher said yesterday that he paid 16 women for their eggs, according to a South Korean newspaper report.

Sung Il Roh, chief of the MizMedi fertility clinic, said he paid for the eggs out of his own pocket, according to a report in Chosun Ilbo. He said he did so without informing Woo Suk Hwang, the high-profile stem cell biologist who used the eggs in his research and has been embroiled in controversy in the 10 days since his American collaborator broke off relations and charged the Korean team with unethical behavior.

Roh's revelations shed new but still incomplete light on a mystery that has only deepened since University of Pittsburgh stem cell researcher Gerald Schatten announced he was pulling out of his 20-month collaboration with Hwang, whose work in the past two years has led to significant advances in the creation of medically promising human embryonic stem cells.

Just weeks before the breakup, Schatten and Hwang had announced plans to launch an international project to supply hundreds of unique colonies of stem cells to researchers around the world.

Schatten's sudden decision to pull out was prompted, he said on Nov. 11, by new information he received that day indicating that Hwang had been less than honest with him about how the human eggs were retrieved for key experiments published in the journal Science in 2004.

Those experiments, which did not involve Schatten but were conducted with assistance from Roh, produced the first-ever colonies of stem cells from cloned human embryos -- a feat that scientists have long predicted could lead to the production of personalized stem cells genetically matched to patients who could benefit from them.

When the research was submitted to Science, Hwang informed the journal that the eggs had been obtained voluntarily and without any payment to the women -- an approach that many ethicists and the U.S. National Academy of Sciences agree is ideal -- to ensure that women do not feel coerced to undergo the egg-retrieval procedure, which carries a small chance of serious ill effects.

It now appears that Roh did pay the women -- about $1,500 each -- according to Roh's comments in Chosun Ilbo. He said he did so without Hwang's knowledge. That detail might help clear Hwang's reputation. Until the recent scandal broke, he was considered something of a national hero in Korea.

According to Roh's published comments, the payments were not illegal at the time, though such payments have been banned since January 2005.

Science magazine's editor in chief, Donald Kennedy, said yesterday that the journal will run a correction if it proves true that the published disclaimer about egg payments was false. Emphasizing that he has no information to suggest the science Roh described in that report is invalid, he said no retraction would be called for.

Still at issue is whether any of the women who gave up eggs for the research were junior members of Hwang's laboratory staff, as some unconfirmed reports have suggested -- an arrangement widely judged as unethical because of the possibility of coercion.

Hwang was scheduled to talk to reporters in Korea today.