BEIJING - A team of World Health Organization experts said yesterday that China has underreported the number of residents affected by the new respiratory illness SARS. Other WHO officials said scientists have confirmed the identity of the virus that causes the illness.

Military hospitals in Beijing have not reported statistics on severe acute respiratory syndrome to municipal health authorities, the WHO experts in China said, adding that they had been banned from disclosing the details of their visits to the hospitals.

"Indeed, there have been cases of SARS - there's no question about that - that have also not been reported officially," WHO virologist Wolfgang Preiser said after a five-day investigation in the capital. "The military seems to have its own reporting system, which does not link in presently to the municipal one."

The WHO experts recommended that Chinese authorities change the reporting system. Chinese Health Ministry officials have maintained that their figures include military hospitals.

Beijing's failure to detect and report all of its SARS cases make it hard to determine the number, but Alan Schnur, WHO's Beijing-based expert in charge of communicable diseases, estimated the number of cases at 100 to 200. Beijing has reported 37 cases and four deaths.

The WHO team said more than 1,000 people with SARS symptoms are under observation in Beijing.

The illness has infected 3,293 people in 22 countries and killed 161. Nearly half of the cases are in China, site of the earliest outbreak, which was covered up for months by the government. China reported 10 new cases yesterday, bringing its total to 1,445 cases and 65 deaths.

Meanwhile yesterday, WHO experts in Geneva, Switzerland, said experiments in monkeys have confirmed that a new member of the coronavirus family is responsible for the illness, an important step toward developing drugs to fight the disease.

Scientists had been almost certain that the new form of coronavirus first isolated from sick patients March 21 by the University of Hong Kong was the cause of SARS. But they could not say for sure until further testing was complete.

Chinese leaders are trying to publicize their commitment to fighting SARS. Over the weekend, Premier Wen Jiabao pledged to redouble official efforts to meet the threat posed by the illness. President Hu Jintao toured hospitals in southern Guangdong province, which is thought to be where the outbreak started.

Chinese officials have said the disease is under control and that it is safe to live and travel in Beijing. WHO experts said they talked to Chinese leaders about their differing definitions of "under control" and "safe."

The WHO experts visited People's Liberation Army hospitals No. 301 and No. 309, and hospitals designated to treat SARS patients in Beijing. Team members said they could not release details of what they saw in the military hospitals without permission from China's Defense Ministry.

The visits followed recent allegations by retired military surgeon Dr. Jiang Yanyong that health officials had ordered a cover-up of SARS-related deaths in the military hospitals. In light of their investigations, WHO team members called the allegations "very credible."

Before investigating Beijing, the WHO experts toured Guangdong, where SARS has claimed most of its victims in China. The team found that region to be ahead of the capital in reporting and prevention measures.

The WHO experts said SARS in China has been confined to urban areas, where health care is better and more affordable. They expressed concerns about the spread of the disease to rural areas without adequate facilities.

Anthony Kuhn is a reporter for the Los Angeles Times, a Tribune Publishing newspaper. Wire services contributed to this article.