International health officials say a top Beijing laboratory is to blame for an outbreak of Severe Acute Respiratory Syndrome (SARS).

Beijing health authorities say they will review laboratory safety after admitting the source of the latest Severe Acute Respiratory Syndrome outbreak was one of the country's top research facilities.

Shigeru Omi, the director of the World Health Organization's regional branch in Manila, says a team of WHO experts would help the investigation.

?Some sort of errors, mistake happened, which are not necessarily in line with the WHO guideline,? Dr. Omi says.

Four people, one of whom has died, have been confirmed with SARS since Friday in China.

Health officials say they have isolated another six suspected cases and have quarantined hundreds of healthy people before the May 1 public holiday.

SARS first emerged in late 2002. It prompted global health warnings, and by July last year about 8,000 people had been infected in a dozen countries. More than 700 SARS patients died.

China was blamed last year for withholding information about the new disease emerging within its borders.

On Friday the WHO congratulated China for publicly releasing news of its latest cases, but three days later the U.N. health agency changed its tone.

During a press conference in Manila, Dr. Omi suggested that the Chinese laboratory had breached safety guidelines many times because the female researcher who tested positive for SARS fell ill almost a month before another doctor from the same lab became sick.

Dr. Omi says another woman who died days earlier, the mother of the female researcher, likely contracted SARS from her daughter.

A year ago, when SARS started spreading from China to cities like Hong Kong, Hanoi, Singapore, and Toronto, the WHO asked China for hospital information on the number of its SARS cases.

Only after weeks of pressure did China release more accurate data. The news that thousands had been infected in southern Guangdong province and the capital Beijing caused a sharp downturn in travel and tourism to the region.