Only half the world's human bird flu cases are being reported to the World Health Organization within two weeks of being detected — a response time that must be improved to avert a pandemic, a senior WHO official said Saturday.

Dr. Shigeru Omi, WHO's regional director for the Western Pacific, said it is estimated that countries would have only two to three weeks to stamp out, or at least slow, a pandemic flu strain after it began spreading in humans.

The first move would be to identify cluster cases and report them to WHO, he said. International teams would then be deployed to investigate the site of the outbreak, the area would be quarantined and antiviral treatment would be administered.

"All the steps have to be done within two to three weeks. As of now ... even reporting the first step, it takes sometimes more than two weeks for half of the cases," Omi said at the end of an Asia-Pacific meeting on bird flu in central Vietnam.

Omi said political commitment to fight the disease is now strong among governments across the region, but public awareness must increase so ordinary people will know what to do if they see a large number of people or birds getting sick at the same time.

Omi attended a meeting with agriculture and health ministers representing the 21-member Asia-Pacific Economic Cooperation forum. On Friday, they endorsed a plan aimed at stamping out bird flu and preparing for a potential pandemic.

Meanwhile, other delegates donned masks, goggles and biohazard suits Saturday morning as they toured a chicken farm in central Vietnam for a firsthand look at hygiene practices.

"These countries have been dealing with avian influenza for several years and have clearly advanced thinking on it, so that's why I wanted to be here this morning to look at the activities that were successful here in Vietnam," said John Lange, the U.S. special representative for avian influenza.

Experts fear the H5N1 bird flu virus, which began ravaging Asian poultry stocks in late 2003, could mutate into a strain easily passed among humans and potentially spark a global pandemic. The virus has killed at least 114 people worldwide. Most human cases have been linked to contact with infected birds.

The farm in Hoa Quy village in the coastal town of Danang has about 7,000 chickens, all of which had been vaccinated. Laying hens were kept in cages in an enclosed coop sprayed with disinfectant.

Much of the poultry in Vietnam and throughout Asia, however, is produced on a much smaller scale, with many households raising handfuls of chickens in backyards. Such farming practices are much harder to control and make it easier for the H5N1 virus to spread.