BEIJING, July 12  A Chinese doctor who exposed the cover-up of China’s SARS outbreak in 2003 has been barred from traveling to the United States to collect a human rights award, a friend of the doctor and a human rights group said this week.

The doctor, Jiang Yanyong, a retired surgeon in the People’s Liberation Army, was awarded the Heinz R. Pagels Human Rights of Scientists Award by the New York Academy of Sciences. His army-affiliated work unit, Beijing’s Hospital 301, denied him permission to travel to the award ceremony in September, Hu Jia, a Chinese rights promoter who is a friend of Dr. Jiang’s, said Thursday.

The Information Center for Human Rights and Democracy, which is based in Hong Kong, also issued a statement reporting the rejection of the travel request. The doctor could not be reached at his home for comment, and a person who answered the phone in the director’s office of Hospital 301 said the situation was unclear, declining to provide further details.

Dr. Jiang rose to international prominence in 2003, when he disclosed in a letter circulated to international news organizations that at least 100 people were being treated in Beijing hospitals for severe acute respiratory syndrome, or SARS. At the time, the Chinese medical authorities were asserting that the entire nation had only a handful of cases of the disease.