A Chinese military surgeon who broke government secrecy to reveal the true scale of Beijing's SARS outbreak in 2003 has been banned from leaving China to accept a human rights award, a rights watchdog said Wednesday.

Jiang Yanyong, 76, was praised as an "honest doctor" by Chinese media after he wrote a letter to reporters saying that Beijing had more than 100 unreported SARS cases. The revelation was followed by embarrassing official admissions and the firing of a cabinet minister.

SARS killed nearly 800 people around the world, including 44 in Toronto.

Jiang has been awarded the Heinz R. Pagels Human Rights of Scientists Award by the New York Academy of Sciences.

But his work unit banned him from leaving China to accept the prize in September, the Hong Kong-based Information Center for Human Rights and Democracy said in a faxed statement.

In rejecting Jiang's request, officials with People's Liberation Army Hospital 301 said the ceremony coincides with the 17th Party Congress, a politically sensitive time, the statement said.

In April 2004, Jiang wrote to China's legislature asking for a reappraisal of the 1989 demonstrations centred on Tiananmen Square, a topic of enormous sensitivity for the governing Communist party.

China's leaders have declared the non-violent protests an anti-government riot. They insist that the June 3-4 crackdown, in which hundreds — perhaps thousands — died, produced a decade of social stability and economic growth.

A little more than a month after writing the letter, Jiang was taken away from his Beijing home for two months. He was later placed under house arrest for several months, family members have said.