A Chinese scholar has been sentenced to 15 years in prison for leaking "state secrets" about the country's missile program in research done at Stanford University in Palo Alto, Calif., the university said today.

Stanford President Gerhard Casper said the school learned this week that Hua Di, a 63-year-old former official in China's missile program who is also suffering from a rare form of male breast cancer, had been sentenced by a Beijing court to the heavy prison term. Hua was arrested after returning to China last year to attend a family funeral. Chinese authorities had told him in Hong Kong that he would have no troubles on the mainland, sources close to Hua said.

Hua's sentence will send a chilling signal to Chinese scholars who collaborate with Americans on security-related projects. Chinese authorities have become increasingly uncomfortable about such cooperation, fearing it will both reveal important strategic weaknesses in China's military modernization drive and highlight the few pockets of excellence, such as missiles, in China's arsenal.

Hua moved to the United States in 1989 and was prominent at the time because he was one of only a few former Chinese officials with a military background who vociferously opposed the June 4 crackdown on pro-democracy students around Tiananmen Square in Beijing. Hua joined Stanford's Center for International Security and Cooperation in July of that year.

At the center, Hua worked closely with John W. Lewis, a Stanford professor who has been criticized in the American academic community for his cultivation of the sons and daughters of high-ranking Chinese Communist officials and his association with a company that sold high-tech communications equipment to a firm owned by China's military.

Hua co-authored several articles with Lewis, including a 1992 study of China's ballistic missile program.

A Hong Kong-based human rights organization said last June that Chinese authorities suspected Hua of leaking missile secrets to the U.S. military and specifically mentioned the 1992 article about China's missile program published in a U.S. journal, International Security.

Stanford's provost, Condoleezza Rice, said in a statement after Hua's arrest that Lewis "had provided evidence to the fact that the source materials for publications written by him and Mr. Hua were provided by approved Chinese authorities or already were available through the Stanford University library."

Hua was a permanent resident of the United States, and it was believed he was about to receive citizenship when he was arrested upon his return to China.