Indonesian health officials said on Thursday that two young men, including one who died a week ago, had proved positive for the bird flu virus in local tests.

I Nyoman Kandun, head of disease control at the health ministry, said specimens had been sent to a Hong Kong laboratory recognised by the World Health Organisation for further testing. Results should be available in the next few days.

Indonesian health officials suspect bird flu in six deaths since July in the world´s fourth-most-populous nation, while the Hong Kong laboratory has confirmed four.

"The PCR (Polymerase Chain Reaction) showed positive for both (men)," said Kandun. "One is a 21-year-old man ... he is still alive and in a stable condition. The other one had died. Both are proven to have had direct contact with dead poultry."

Bird flu has killed more than 60 people in four Asian nations since late 2003 and has been found in birds in Russia and Europe.

One of the greatest fears of experts is that the H5N1 bird flu virus will mutate to become easily passed between humans, triggering a pandemic. The current H5N1 strain cannot be easily transmitted by people. Millions have died in past flu pandemics.

Authorities in Indonesia say they have found infected chickens that were asymptomatic of the virus, which could raise greater threats to human by making it harder to detect.

Health experts say the finding was bad news but more information was needed as there are many different strains of H5N1. Many have low pathogenicity and are relatively harmless, and only some have proven to be deadly for birds and humans.

Some species of waterfowl, like ducks and geese, are natural hosts of the H5N1 and do not fall ill from it. But the virus has always been known to be virulent in chickens, but they typically fall sick quickly and die within 24 hours of contracting it.

ASYMPTOMATIC CHIKENS A DANGER

Health Minister Siti Fadillah Supari said chickens without symptoms had been found among those kept in backyards, while commercial chickens usually died quickly when they contracted the disease.

"Certainly, it poses a greater danger for humans because we don´t know whether the poultry are infected as they do not show any symptoms," Supari said.

The country has come under fire for reluctance to carry out mass culling of chickens in infected areas like those conducted in some other countries.

Supari said Indonesia had received 60,000 doses of the anti-viral drug Tamiflu, mostly aid from neighbouring Australia. Tamiflu will be distributed to 44 designated hospitals across the sprawling archipelago.

Indonesia cumulatively has had nearly 90 human cases under observation for suspected bird flu, but most have proved negative.

The virus has spread to 22 provinces out of 33 in Indonesia´s sprawling archipelago, killing more than 10 million domesticated birds since late 2003.

One of the difficulties in controlling the disease is that a large number of people in both rural and urban areas of the country keep a few chickens and other livestock.