The World Health Organization said today that Chinese data on the spread of Severe Acute Respiratory Syndrome still left much to be desired.
Most glaringly, authorities in the capital Beijing have no idea where half the city's patients contracted the virus, WHO spokeswoman told reporters.
She said a lot of vital data is still missing, meaning it is premature to say the situation in Beijing is improving as some local officials have suggested.
"You are dealing with a whole host of unknowns," she said. "When we deal with unknowns, we can't make clear conclusions."
Unprepared local hospitals, whose lack of control measures made them a breeding ground for the disease, were a major factor fueling the rapid spread of SARS in Beijing, a WHO virologist, previously told reporters.
In the capital, a city of 13 million people, the problem was that ordinary patients seeking treatment for flu or other respiratory diseases - the early warning symptoms of SARS - were becoming infected with the atypical pneumonia after being grouped together with SARS patients during a chaotic period of diagnosis, he said.
Beijing has reported 114 fatalities from SARS - about one-fifth of the global death toll - and 2,177 confirmed SARS patients and 1,425 suspected cases.
China's nationwide death toll now stands at 230 from a total 4,805 reported infections.