A prominent South Korean scientist stood by his purported breakthroughs in stem cell technology Friday amid accusations he falsified key evidence, but he still requested that a landmark scientific article be withdrawn due to errors.

Hwang Woo-suk's article, published by the journal Science in May, purported to show how individual stem cell colonies were created for 11 patients through cloning — a key breakthrough that scientists hoped could eventually lead to finding cures for illnesses like diabetes and Parkinson's disease.

Hwang said he asked the journal to withdraw the report due to problems with the accompanying photos, apologizing for "fatal errors and loopholes in reporting the scientific accomplishment." Previously, Hwang's team told Science that some duplicate photos of the same stem cell colonies had accidentally been printed, but the journal's editors said the mistake did not affect the findings.

Still, Hwang insisted the findings behind the article were sound, and that he would prove it in coming days.

"Our research team made patient-specific embryonic stem cells and we have the source technology to produce them," Hwang told a news conference.

Hwang's work has been under fire for weeks, but the latest round of questions came Thursday when a former collaborator accused him of pressuring a lab worker to forge evidence. Roh Sung-il, chairman of the board at Mizmedi Hospital and a co-author of the article, maintained Friday that Hwang still was not telling the truth.

"He's avoiding taking the responsibility that he should take," Roh said, questioning the validity of Hwang's claims that he created 11 stem cell colonies.

"Nine stem cells appear to be fake and two others are not confirmed yet," Roh, who provided Hwang with human egg cells for the research, told The Associated Press.

The researcher from Roh's hospital who reportedly was ordered to fabricate results defended Hwang on Friday. In an interview with KBS television in the United States, where he is assigned to the University of Pittsburgh, Kim Sun-jong said he had personally seen eight stem cell lines and another three being nurtured.

"The stem cells were cultivated through normal procedures and six members of Hwang's research team verified them every morning," Kim told KBS.

Hwang insisted earlier the 11 stem cell colonies were created "without 1 percent of doubt." He said some of the cells he created died after being contaminated, but that cells were now being unfrozen that would prove the validity of his work within 10 days.

But Roh said Hwang's attempts to prove the authenticity of the experiments would not work. Roh said Hwang told him Thursday there were no embryonic stem cells remaining from the experiments because all the colonies died in the lab.

"What can I say if Hwang changes the remarks he made with his own mouth yesterday," Roh told AP.

Pittsburgh researcher Gerald Schatten already asked that Science remove him as the senior author of the report, citing questions about the paper's accuracy. Donald Kennedy, editor of Science, said the journal welcomes inquiries on the article by authorities in Korea and at Pittsburgh.

After an emergency meeting chaired by Prime Minister Lee Hae-chan, the South Korean government said it would wait to take further action until after an internal probe by Seoul National University, where Hwang works. The university announced Friday it had appointed a nine-member investigation panel — seven from within the university and two from other South Korean institutions — to look into the allegations.

Hwang is considered a national hero in South Korea and is strongly supported by the government, which has given him nearly $25 million for his research. The allegations have shocked the country, even sending shares on the South Korean stock market plummeting downward Friday morning.

Hwang's work has recently come under a cloud of suspicion. Last month, he publicly apologized after admitting that, despite earlier denials, he used eggs from two female scientists in his lab — a violation of international ethics guidelines.

Hwang has also stepped down as head of the World Stem Cell Hub, an international project launched in October aimed at finding treatments for incurable diseases.

Douglas Melton, co-director of the Harvard Stem Cell Institute, said Thursday through a spokesman he was "truly saddened" to hear the allegations against Hwang. But, he said, "stem cell science holds too much promise to allow this incident to detract from the careful, closely supervised work being done in the U.S."

Other scientists stressed Thursday that the fraud accusations against Hwang have not been proven.

"We have to give him the benefit of the doubt right now," said cloning researcher Peter Mombaerts of Rockefeller University in New York.

He said Hwang and a colleague appeared confident and believable when top cloning researchers questioned them about the work at a scientific meeting Nov. 9 before the accusations arose.

"They withstood the test," Mombaerts said.

But if substantial fraud is proved, scientists said, it would cast doubt on Hwang's other work, including his report last year of the first cloned human embryos from which stem cells were extracted, and his announcement in August of the first cloning of a dog.