-- The Chinese government said Friday that very few samples of bird flu virus collected here over the past two years showed resistance to a key influenza drug, contradicting complaints by international researchers that Chinese veterinary practices had rendered the drug useless if the virus were to spread to people.

Jia Youling, a senior Agriculture Ministry official who serves as the country's chief veterinary officer, acknowledged that Chinese farmers have used the drug, amantadine, which is meant for people, on chickens and other poultry. But he said the practice was banned last year and denied that it had resulted in the bird flu virus developing a resistance to the drug.

"Some people have said that because China once used amantadine, disastrous effects have now been brought about on the global prevention of avian flu," he said at a government news conference. "However, I think that statement is quite unfair."

Jia suggested instead that veterinary practices in Southeast Asia were to blame for strains of bird flu becoming resistant to the drug.

Citing animal health experts, The Washington Post reported in June that Chinese farmers had used amantadine to treat bird flu in chickens with the approval and encouragement of government officials. As a result, researchers have concluded the drug will not be effective if the avian influenza mutates into a form that can spread among humans and causes a global pandemic.

Amantadine is one of two main types of medication available for treating human influenza. The other, oseltamivir, sold under the product name Tamiflu, is more expensive and more difficult to produce in large amounts. Health experts are now evaluating whether another drug, zanamavir, sold as Relenza, could also be used in widespread treatment of the virus.

The Chinese government has denied that it urged farmers to use amantadine to suppress bird flu outbreaks. But Jia said some Chinese poultry farmers have used the drug in the past on the advice of the Merck Veterinary Manual, a leading guide for the veterinary profession around the world.

The manual's online edition lists amantadine under the prevention and treatment section of its entry on influenza. It says the drug "reduces the severity of influenza in some avian species, but amantadine-resistant virus frequently emerges."

Jia said "only very limited samples" of the bird flu virus tested in China last year and none of the samples tested this year had mutated and become resistant to amantadine. By contrast, he said, the vast majority of bird flu virus samples tested in Southeast Asia had become resistant. He noted that governments there had not followed China's lead in vaccinating large numbers of poultry against the influenza.

"Due to the inadequate vaccination in these countries, farmers had to resort to the use of amantadine to prevent avian flu, which may lead to the mutation of avian flu viruses," he said. "So I don't think it's fair to blame China."

The Chinese government did not immediately provide data on the number of cases tested and the number that showed resistance.

Jia's assertions contradict international researchers, including experts at St. Jude Children's Research Hospital in Memphis, one of the premier private influenza research institutions in the world. Experts there reported last month that bird flu strains in East Asia, particularly in China, had become more resistant to amantadine during recent years. They also said the mutations in China did not appear to be random, adding they could be the result of treating chickens with the drug to prevent bird flu.

Animal health experts have also said the use of amantadine to treat livestock was not common in Southeast Asia because of the drug's limited availability and the high cost of importing it to countries there.

Since January 2004, more than 60 people have died of bird flu in Vietnam, Thailand, Cambodia and Indonesia. And the virus has spread to Europe's eastern border. China reported three new outbreaks in poultry in the past week, but it has not reported any infections in people.

Correspondent Alan Sipress in Jakarta, Indonesia, contributed to this report.

A doctor vaccinates a vendor at a poultry market in Beijing. Although bird flu has been found among poultry in China, no human cases have been reported.