WHO officials in Beijing said Chinese authorities had granted WHO's request for up to 20 live samples, which will be analyzed in international laboratories to improve understanding of the killer virus.

"We hope that within a matter of days, maximum of weeks, they will provide the virus samples," Julie Hall, coordinator of communicable disease surveillance and response in WHO's Beijing office, told reporters.

The two sides are working out the logistics, including how to ship the samples and which lab they will go to, Hall said.

The shipment is "significantly larger" than the last one China provided, which consisted of five live viruses from poultry in 2004. It did not provide samples in 2005.

WHO enjoyed good cooperation with China's ministry of health, which has shared viruses from human cases.

WHO officials expressed hope the agreement could open the way for more regular sharing of viruses, which is crucial to determining the different types of strains of the deadly bird flu virus that exist and how they affect humans differently.

"We hope this is now the start of regular sharing that doesn't involve the degree of negotiations we've had and we'll see not only a one-off shipment but regular shipments," Hall said.

China has reported 34 outbreaks among poultry since the beginning of last year and 15 confirmed human cases of bird flu, resulting in 10 deaths.

The virus has killed more than 100 people worldwide since 2003, mostly in Asia. It has spread from Asia to Europe and Africa in recent months.