SEOUL, Nov. 24(Xinhuanet)-- South Korean renowned stem cell expert Hwang Woo-suk Thursday admitted using ova donated by his two fellow researchers at a press conference.

Slowly saying in a depressed tone, the famous professor delivered his apology to South Korean people for the"embarrassing and tragic" news.

Hwang said 16 females donated eggs to his laboratory during 2002 and 2003 period of time, including two junior researchers in his team.

He said he declined several times to the offer of the two researchers who expressed willingness to donate their ova for Hwang's groundbreaking research of stem cells in 2003, when his research suffered from shortage of human eggs.

Hwang said he knew the fact that the two female researchers donated their ova under false names only after the world famous English journal of Nature reported the issue last year.

At the televised press conference, Hwang also announced resignation as head of the World Stem Cell Hub.

The hub, a government-funded center that opened in October, is the world's first facility geared toward using stem cell lines for the possible treatment of various incurable diseases.

Hwang stunned the world by announcing his team first cloned human embryo and extract stem cells from it in May last year.

Hwang also attracted attention this August by announcing his team cloned a dog for the first time in the world.

Controversy surfaced when Gerald Schatten, a professor at the University of Pittsburgh and a key partner in Hwang's research, issued a personal statement last week, announcing he stopped collaborative research ties with Hwang due to suspicions of unethical activity in ova procurement.

Medical experts say the key to the dispute lies in the Declaration of Helsinki, an international charter adopted in 1964 by the World Medical Association that outlines ethical principles for medical research involving human subjects.

The declaration states that"when obtaining informed consent for the research project the physician should be particularly cautious if the subject is in a dependent relationship with the physician or may be under duress."

Earlier Thursday, South Korean Ministry of Health and Welfare in a briefing defended Hwang and his team, saying the Declaration of Helsinki only calls for discretion and not an outright ban. Enditem