American stem cell scientist Gerald Schatten says he trusts 300 percent the thesis of cloning pioneer Hwang Woo-suk that was presented to Science magazine in May.

Hwang's research partner Ahn Cu-rie on Monday said Schatten told her over the phone Saturday that he still supports Hwang and that he will help defend the thesis.

Schatten is a University of Pittsburgh professor and a leading American stem cell expert who recently ended his 20-month partnership with Hwang after the controversy over ova donations broke out.

The two men are believed to have exchanged stem cell photos via email and held constant discussions daily before the thesis was presented to Science in May.