Roy Wadia, a WHO spokesman in Beijing, said China had been giving the organization updates from Sichuan province on the disease blamed on the Streptococcus suis bacteria. But more tests were needed to "eliminate other possible scenarios," he said.

"Doing tests of different sorts is something we would recommend ... in any outbreak situation, especially in one of this scale," Wadia said.

Some 208 people have become ill in dozens of villages and towns in Sichuan province since June, China's Health Ministry said Friday, mostly farmers who butchered or handled sick pigs. Fifteen remain in critical condition.

No person-to-person infections have been reported.

International experts on Streptococcus suis have also raised concerns about China's outbreak, saying it is highly unusual for so many people to fall sick and die suddenly from the disease. They recommend the strain be sent to another lab for testing.

Symptoms of the disease include high fever, nausea and vomiting, followed by meningitis, hemorrhaging under the skin, toxic shock and coma in severe cases. Some patients also suffered organ failure.

Chinese health officials say that the strain is extremely virulent and killed one farmer in as little as two hours. But they have assured the public the disease was under control.

Beijing was criticized in 2003 for being reticent about sharing information on its first outbreak of Severe Acute Respiratory Syndrome, which emerged from the country's south and killed nearly 800 people around the globe.

Emergency notices were issued this week by the central government ordering tighter controls on the slaughter and sale of pigs to curb the spread of the Streptococcus suis bacteria. Officials and farmers who fail to obey have been threatened with severe punishment.

News reports last week said some officials were dismissed after failing to enforce a ban on the export of pork from affected areas of Sichuan, which has one of China's biggest pig populations.