Updated

World Health Organization investigators said Wednesday that China has unreported cases of the deadly SARS virus in military hospitals in Beijing and has barred release of details about them.

The comments, which came after WHO experts visited two military hospitals, raised fears the illness may be more prevalent in China than it has acknowledged. China has officially reported 65 deaths and more than 1,300 cases of the illness.

The team paid visits to the Nos. 301 and 309 military hospitals in China's capital on Tuesday and later said they saw severe acute respiratory syndrome patients and received data on new cases. But they said officials told them not to release details on them and they wouldn't say how many cases there were.

"There indeed have been cases of SARS, there is no doubt about that, that have not been reported officially, in that the military seems to have its own reporting system that doesn't link in presently to the municipal one," said WHO team member Dr. Wolfgang Preiser told a news conference.

The WHO investigators blamed the discrepancy on a "reporting problem" in the Chinese system, in which the military hasn't been informing civilian authorities about its cases.

Outsiders have accused China of underreporting cases and possibly suppressing information, but the WHO investigators didn't say they considered the newly disclosed cases evidence of a cover-up.

Rumors have circulated that there were many unreported cases of SARS in Beijing's secretive military hospitals. A senior Chinese military surgeon said last week that China's capital had several times as many cases as had been reported.

Henk Bekedam, the WHO representative in Beijing, said the data received there by the team "corresponds to rumors" about additional SARS cases, but he didn't elaborate.

Another WHO official estimated on Wednesday that the city of Beijing has 100 to 200 cases of the deadly SARS virus — far more than the 37 publicly reported. Most of the cases by far have been in southern Guangdong province.

Alan Schnur, head of communicable disease control in WHO's Beijing office, said his figure was based on information gathered from health care workers and other sources and his own knowledge of the Chinese capital's health system.

"One hundred to 200 cases," Schnur said. "Those are cumulative probable cases since March, when the disease was first picked up in Beijing. That's my 'guesstimate.'"

In hard-hit Hong Kong, authorities on Wednesday reported five more SARS deaths, pushing the death toll here to 61.

Meanwhile, three babies born to Hong Kong mothers with SARS have difficulty breathing and look like they may have the illness although they initially tested negative, a pediatrician said Wednesday.

The babies were delivered prematurely by Caesarean section to avoid complications from medicines used to treat SARS and because the mothers were seriously ill, Dr. Hon Kam-lun told The Associated Press.

All three tested negative for the coronavirus that is believed to case SARS, but Hon said they "increasingly resemble" SARS cases. It is possible the premature births also made them susceptible to health problems, he said.

Two have a fever, which is common in SARS patients, said Hon, who teaches at the Chinese University of Hong Kong and has been monitoring the babies.

One of the mothers, a 34-year-old, was among nine people whose deaths were reported on Tuesday, Hong Kong's biggest one-day total yet. The disease has sickened 1,232 people here and killed at least 56.

The other two mothers are still alive. Hon said he had no information on their conditions, but he said they were young.

All three mothers were taking the anti-viral drug ribavirin, Hon said, and doctors had been worried about side effects in pregnant women.

Hong Kong doctors have been treating many SARS patients with a combination of ribavirin and steroids. They say it has been effective in many cases.

But in a discouraging development, the acting chief executive of the Hospital Authority, Dr. Ko Wing-man, was quoted Wednesday as saying 10-20 percent of Hong Kong's SARS patients were not responding well to treatment. The report on RTHK radio did not specify which types of treatment he was talking about.

Hong Kong's health secretary, Dr. Yeoh Eng-kiong, had predicted previously that 95 percent of SARS victims — assuming they had no serious pre-existing health problems and got early treatment — would recover with help from ribavirin and steroids.

Also on Wednesday, Hong Kong researchers said they have completed a new gene map of the suspected SARS virus and they know it came from animals — a finding they hope will eventually lead to a vaccine.