The sharing of laboratory samples from H5N1 bird flu victims is essential to keep track of any mutations in the virus that might herald the development of an even deadlier pandemic strain of influenza, according to the World Health Organisation.
"The one country that has not yet shared viruses with us this year is Indonesia," David Heymann, WHO assistant director general for communicable diseases, said in a conference call with journalists.
Heymann said that by not sharing samples with WHO research laboratories, Indonesia was putting its own population in danger because anti-flu vaccines developed by industry would not contain components of Indonesian bird flu infections.
"The second thing Indonesia is doing is putting the public health security of the whole world at risk because they're not sharing viruses," he added.
Indonesia had stopped sharing virus samples with foreign laboratories in December 2006 because it feared multinational drug companies could use them to develop vaccines that were not affordable for poor countries.
It is seeking changes to the global flu surveillance system to ensure developing countries get a fair deal.
Negotiations are under way to reach an agreement on detailed international virus sharing guidelines at a special meeting of the WHO's member states in November.
Tensions over the issue had seemingly eased in May after talks on virus sharing began, and Indonesia said it had resumed sending H5N1 specimens to a WHO laboratory in Tokyo.
However, Heymann revealed Monday that the three specimens Indonesia sent to Tokyo did not have live flu viruses in them, and two were from the same person.
Twenty-seven of the 56 human cases of H5N1 bird flu recorded by the WHO this year have occurred in Indonesia. It also has by far the highest death rate, accounting for 23 out of the 34 deaths recorded in six countries this year.
China had shared samples of viruses with the WHO's international network of laboratories in June, Heymann said.
Meanwhile, Vietnam has been trying to send samples, but the shipment has not been cleared yet because of problems with ensuring the consignment complies with strict biosafety rules, he added.