South Korean cloning pioneer Woo Suk Hwang Woo apologises for ethical lapses during a news conference in Seoul.© LEE JIN-MAN/AP/EMPICS

Woo Suk Hwang admitted today that his landmark research on stem cells used eggs from two junior researchers and from paid donors.

Hwang's statement, made at 2 pm Korean time on 24 November, was broadcast live on all three of the country's main stations. His admission, about the first work that harvested stem cells from cloned human embryos, floored viewers and will surely reverberate in the international scientific community.

The confession, which bore out suspicions first raised in Nature in May 2004 (see 'Korea's stem-cell stars dogged by suspicion of ethical breach'), was accompanied by his decision to resign from all government and social organizations as well as the World Stem Cell Hub, an initiative launched last month to share stem cells derived at the Korean laboratory. The future of the initiative is now uncertain.

Hwang said that he did not know about the source of the eggs until the news story in Nature. But after this he denied that eggs had come from his research staff. According to Korean media, he asked for understanding, stating: "The fact that I had chosen to protect my researchers would not excuse me from having withheld the information. But, please know that it never was my deliberate intention."

The pioneer added that both he and his graduate students were unaware of the ethical implications of using eggs from junior researchers. Many observers have pointed out that the procedure of donating eggs is painful, invasive and potentially dangerous.

What next?

The reaction in South Korea has been sympathetic. Various local news outlets have run stories about women lining up to donate eggs, and have emphasized that the use of a subordinate's eggs in research did not violate Korean legal or ethical codes in 2002-03, when the procedures were carried out. Rules have since been made to prevent this practice.

Still, the Korean Bioethics Association thinks that more investigation is appropriate. Young Mo Koo, from the University of Ulsan, says that it is difficult to believe that Hwang did not know about the donations before the 2004 Nature article. He also questioned a statement from a health ministry investigation, which said that the donations by the laboratory members had been made voluntarily. "Further investigation is needed," Koo told Nature.

Hwang says he will not give up his research. Whether the scientific community will accept him back remains to be seen. Colin McGuckin, an expert in regenerative medicine at the Centre for Life in Newcastle upon Tyne, UK, says, "It has always been my policy that ethics and morals start at home in the lab. We must protect the young staff working in stem-cell medicine. But let us not forget that Korean stem-cell research was not just about one man. Much good research has been done there."