Scientists battling the constantly mutating virus have come up against resistance from certain countries, notably Indonesia, to share information without in return being guaranteed access to vaccines.
"We really are all in the same boat," WHO director general Margaret Chan said at the opening of an intergovernmental conference in Geneva.
"A pandemic will reach every corner of the earth and it will do so within a matter of months.
"The sharing of currently circulating viruses is the only way to monitor the emergence of drug-resistant strains."
Indonesia suspended the sharing of its specimens in December 2006, complaining that impoverished countries were giving away examples of their viruses to Western laboratories for free but were then unable to afford the vaccines produced.
It did release samples from four victims to the WHO-led international bird flu monitoring network in August, but is still far from sharing samples from all of its 113 cases of bird flu, 91 of which resulted in death.
Indonesia is the country most affected by the H5N1 bird flu virus, which since 2003 has struck down 335 people in 12 countries, killing 206 of them, according to the latest official WHO figures.
All of those taken ill so far were infected directly by an animal. But the WHO fears the virus will mutate to allow human-to-human transmission, provoking a pandemic like the Spanish flu of 1919 which killed around 40 million people.
Sharing virus specimens is the key to preventing that, urged Chan.
"The sharing of viruses is the foundation of risk assessment. The analysis and the comparison of viruses give us the first clues, the first early warning, that the virus may be evolving in a dangerous way," she said.
Under a proposal submitted to the Geneva conference, Indonesia wants a link between information-sharing and access to vaccines.
Their submission stipulates that "access to virus is provided within the framework of the establishment of a global vaccine stockpile... formulated by the WHO and endorsed by member states."
Indonesia is insisting on "the recognition of sovereign rights of states over their biological resources," stipulating that the "authority to determine access to influenza virus rests with national governments."
In a report to the director general, the WHO suggests a system of advance purchases, or "advance commitment mechanism."
That would allow countries with production capacity for a flu vaccine to agree in advance to release set quantities paid for in advance.
According to the WHO, that would mean that poor countries "would have some guaranteed access to pandemic influenza vaccines."
The WHO hopes that between now and 2010 production of an avian flu vaccine can be ramped up to 4.5 million doses a year.