The World Health Organization (WHO) is working closely with the China laboratory tests to diagnose SARS patients more quickly and accurately, WHO Representative in China Henk Bekedam said in an exclusive interview with China Daily Wednesday.

The research is expected to run for several months, Bekedam said.

Bekedam said that the current case definitions for SARS adopted by China are very close to those used by the WHO.

"Because we do not have proper diagnostic tests in the laboratory now, we have to depend on clinical symptoms in diagnosing SARS patients in all SARS-affected countries,'' he said.

He pointed out that current clinical tests are not sensitive enough.

"Maybe in one of the clinical test, a man is positive. But in another test, he is negative. Then it still takes time to decide whether he is a SARS patient,'' Bekedam explained.

The representative said a test was needed to quickly diagnose a person with SARS.

"So if there is a problem with the diagnostic criteria, it is not a problem for only China, but for all the countries suffering from SARS,'' he said.

Bekedam was answering a question arising from foreign news reports claiming that the sharp decline in new SARS infections was due to less strict diagnostic standard.

According to the Ministry of Health, the Chinese mainland reported no new confirmed SARS cases and no deaths from the virus in the 24 hours to 10 am Wednesday.

Only four new suspected cases were found on the Chinese mainland. Two were reported in Beijing, while the others were from Southwest China's Sichuan Province and South China's Guangdong Province.

There are still 908 suspected cases under observation and 1,321 SARS patients under treatment in hospitals across the country.

The WHO said on Tuesday that the majority of viral diseases are most contagious early on - usually in the first few days following the onset of symptoms. But viral shedding during the initial phases of SARS infection is comparatively low.

Available tests are unable to reliably detect the SARS virus or its genetic material during the earliest days of illness, according to the health agency.

"This poses a particular challenge for SARS control, as patients are still capable of infecting others during that initial phase,'' it said.

Bekedam's views were echoed by Liang Wannian, deputy director of the Beijing Municipal Health Bureau.

"Such tests would be able to reduce the time for diagnosis of suspected SARS cases,'' he said.

It presently takes seven to 10 days to decide whether a suspected SARS case is infected with the virus or has another disease.

As of Wednesday, the total number of suspected SARS cases in Beijing was 718.

Of the 718, hundreds are still in hospital in Beijing but a precise figure was not available Wednesday.

In the campaign against SARS, the Beijing municipal government has decided that it would rather mistakenly classify a person as a SARS patient than risk under-counting of cases.

Editor: Liao Ming