Seoul National University says it has effectively shut down the laboratory of cloning pioneer Hwang Wo-suk at its School of Veterinary Medicine.

The university on Monday said it has prohibited access to research data at the lab without permission of the investigative committee on Hwang's research and suspended stem cell research until suspicions are cleared.

After seven hours of interrogation Sunday, Hwang on Monday morning appeared again for questioning at the university.

The committee's nine members will look into how Hwang's paper published in May by the journal Science was fabricated and if cloned stem cells really existed.

They will also peruse through Hwang's past work involving the 2004 paper and his breakthrough cloning of the dog "Snuppy" and the calf "Younglong."

The panel will also question Roh Sung-il, the board chairman of MizMedi Women's Hospital in Seoul and a key collaborator of Hwang.