The World Health Organisation urged countries on Friday to review safety in laboratories after finding that this year’s outbreak of SARS likely originated in China’s National Institute of Virology in Beijing.

The WHO said at least four laboratory workers may have been infected with the virus that causes severe acute respiratory syndrome at the institute at the start of an outbreak in March that killed one person and infected nine others.

“In light of the investigation, WHO believes that member states should carefully review biosafety standards and strengthen them to avoid further incidents,” Shigeru Omi, regional director of WHO’s western Pacific region, said in a statement.

The WHO said an inactive SARS virus was used several times in early 2004 in experiments at the Beijing laboratory when the four workers were present. China’s Health Ministry said on Thursday that the outbreak originated in the laboratory.

The WHO said it would work with countries to develop strategies to strengthen safety, including a reduction in the number of laboratories storing and working on SARS. It also said scientists working with highly pathogenic viruses such as SARS needed to handle inactive material with the utmost caution.

“Disease detection systems need to be designed to take these risk factors, as well as clinical information, into account, and to be robust enough to ensure that nobody slips through the net and evades detection,” it said.

SARS first emerged in southern China in late 2002 and spread around the world to infect 8,000 people in nearly 30 countries, devastating the airline and tourism industries. Nearly 800 people died.

China, hardest hit after hiding the extent of the disease in the early stages, declared victory over that outbreak in July 2003. The WHO declared this year’s outbreak contained in May.