Disgraced stem-cell scientist Hwang Woo-suk testified on Tuesday saying he was duped by junior researchers into publishing bad data but South Korean prosecutors at the trial sought to prove he was guilty of fraud.

Hwang, once celebrated as a national hero, was indicted in May after prosecutors said he was the mastermind of an elaborate scheme to manipulate results to make it look like his team had actually produced stem cell lines through cloning human embryos.

"I believed the test results brought to me by researchers that supported the findings in the papers," Hwang said. He added the results wrongly showed that his team's stem cell research was successful.

Prosecutors have charged Hwang with misusing and embezzling 2.8 billion won ($2.96 million) in state funds and private donations as well as fraud and violating bioethics laws in procuring human eggs for his research.

Misuse of state funds carries a penalty of up to 10 years' jail, while violating the bioethics law can lead to three years' imprisonment, prosecutors have said.

Hwang, 53, dressed in a dark suit, spoke with increased emotion when he responded to questions from prosecutors about the integrity of the science in his team's work.

"We still want to believe the veracity of the stem cell lines, which we hope will be verified by a world-renowned lab, not some incompetent committee from Seoul National University (SNU)," Hwang said.

An investigation panel at SNU, where Hwang once worked, said in a report in January Hwang's team deliberately falsified key data in two papers on embryonic stem cells that have since been retracted by the U.S. periodical Science.

His reported breakthroughs in stem cell research had raised hopes because it seemed to hasten the day when genetically specific tissue could be grown from embryonic stem cells to repair damaged organs or treat diseases such as Alzheimer's.

This was the second day of hearings for Hwang before a three-judge panel at the Seoul Central District Court. There was a one-day hearing last month.

In the opening statement, Hwang's lawyer said the research leader was unaware of the fabrication in the data for two landmark papers and blamed junior researchers for mishandling samples that were being cultivated.

Hwang's team once basked in global acclaim for groundbreaking achievements that put South Korea at the global forefront of cloning and stem-cell research.

In a paper published in the periodical Science in 2004, Hwang's team said it had developed stem cells from a cloned human embryo. In 2005, Hwang's team published another paper in Science saying it had produced tailored embryonic stem cells.