South Korean researcher Hwang Woo- suk made a public apology on Thursday for fabrication in his two papers published in U.S.-based journal of Science, while insisting someone swapped the stem cells.

"I sincerely apologize to the nation for using erroneous data in the papers," said Hwang at a press conference held at Press Center Building in central Seoul.

His apology came two days after Seoul National University (SNU) concluded Hwang had never created embryonic stem cells and that he played a part in the fabrication of data for at least one of his papers published by Science in 2004 and 2005.

The researcher admitted at the press conference he had paid a " small amount" of compensation to ova donors and used ova donated by two fellow researchers in his team during the stem cell research.

However, he maintained his previous stance that someone switched his original stem cell lines with vitro fertilized samples brought from MizMedi Hospital, a famous fertility clinic in Seoul.

Hwang hinted the MizMedi Hospital, who was responsible for procuring human eggs for Hwang's team, also played major role in the scandal.

Several researchers of the hospital assumed important job in Hwang's researches on stem cells, according to Hwang.

Hwang claimed it was MizMedi Hospital who was responsible for cultivating stem cell lines and conducting DNA cross-checks on the stem cell lines.

The embattled researcher mentioned three researchers from the hospital that he believes had conspired against his work.

"These researchers said repeatedly that they had confirmed the authenticity of stem cell lines for the 2004 and 2005 paper," he said, but admitting that he did not check up on their research results.

At the same time, Hwang strongly insisted his previous allegation that his team holds crucial "source technology" of producing stem cells.

Hwang claimed his team's technology of cultivating blastocysts is still in the leading place in the world.

He also said he is willing to transfer such technology to any research team of South Korea, so that South Korean scientists could continue keeping a head in such field.

A blastocyst is an embryo at a stage where it consists of 60 to 120 cells. With its inner cells still undifferentiated, the blastocyst is the crucial sources of embryonic stem cells.

Stem cells are primal undifferentiated cells which retain the ability to differentiate into other cell types. Medical researchers believe stem cell research has the potential to find new way to treat hard-to-cure diseases by developing stem cells to specific tissues or organs.

In the paper published in February 2004 by Science, Hwang's team claimed it successfully cloned human embryo and extracted a stem cell line from it for the first time in the world.

Hwang's team claimed in the paper published by Science in May 2005 that it successfully produced 11 patient-tailored stem cell lines. The development cited in the paper was widely viewed an important progress in the therapeutic cloning research.

Due to the two papers, Hwang became the top-ranking stem cell scientists in the world and won huge fame in South Korea.

Thursday's press conference was the third one held by Hwang since ethical and authenticity controversy surrounding his researches erupted in late October 2005.

During the one-hour press conference, a score of Hwang's fellow young researchers also appeared before two hundred of reporters, extending their support to Hwang.

While some local people held anti-Hwang demonstration outside the meeting venue, calling him a cheater.

Early Thursday, South Korean prosecutors raided the house of Hwang and 25 other locations to secure evidence on his fabrication of stem cell research data in two papers published by Science.

Prosecutors were also reportedly to try to check details of e- mails exchanged between Hwang's team and the researchers of MizMedi Hospital.

A special investigation team was already formed by the Supreme Prosecutors' Office and the Seoul Central District Prosecutors' Office on Wednesday.

South Korean government already also decided on Wednesday to stop financial aid and to strip him of his status as the nation's first "Top Scientist."

Science and Technology Vice Minister Choi Suk-shik said on Thursday that the government will stick to its previous stance of cutting subsidies to Hwang since he has already acknowledged of having fabricated data in his study.

Source: Xinhua