Updated

Japanese officials planned Monday to slaughter 82,000 more chickens after signs of bird flu were detected at a farm northeast of Tokyo (search), and Hong Kong said it would shut farms and kill all poultry in the territory if the virus is found on more than one farm.

Pacific rim disaster experts met in Australia to discuss how to respond to a possible human flu pandemic. And Swiss drug company Roche Holding AG (search) was reportedly in talks with Chinese officials about jointly producing its anti-viral medication Tamiflu, considered one of the few drugs likely to be effective in a global epidemic.

The latest Japanese outbreak occurred at a farm in Ibaraki (search), just northeast of Tokyo, officials said. The farm was inside a quarantined area where authorities had already found signs of the disease and culled around 1.5 million birds, prefectural livestock farming chief Taro Imai said.

Antibody tests showed the chickens had been exposed to a bird flu virus from the H5 family but survived, Ibaraki officials said in a statement. No active bird flu viruses were found, Imai said.

Bird flu hit Japan last year for the first time in decades. Officials say the strain that hit the country, H5N2, is less virulent than the H5N1 variety that has ravaged Southeast Asia since 2003 and killed at least 62 people there.

Most human cases have been traced to direct contact with sick birds, but health officials fear the H5N1 virus could mutate into a form that is easily passed to and between humans, possibly setting off a deadly flu pandemic.

Eddy Chan, Hong Kong's deputy secretary for health, welfare and food, said the government would kill all poultry in the territory if the H5N1 bird flu strain is found in chickens at two separate farms.

"We can't wait for it to happen in a third farm before taking action," Chan told lawmakers at a legislative meeting.

Chan added that all of Hong Kong's 2,260 poultry farms would likely be closed for good under the plan.

The first recorded outbreak of H5N1 in humans was in Hong Kong in 1997, when the virus infected 18 people and killed six, according to the World Health Organization.

Vietnamese officials said Monday they had killed 400 poultry in backyard farms after about 800 birds from 20 backyard farms died en masse.

Hoang Dang Nguyen, director of the animal health department in Bac Giang province, about 35 miles northeast of Hanoi, said the poultry were culled even though the dead birds tested negative for the H5N1 strain.

Countries around the world have rushed to stockpile Tamiflu, Roche Holding AG said of its anti-viral drug.

"We are talking with a number of Chinese authorities to see what is the best way to address the issue at this point," the Hong Kong newspaper South China Morning Post quoted Roche's chairman and chief executive officer, Franz Humer, as saying at a weekend conference of business and city leaders in Shanghai.

Roche's office in Shanghai refused to comment by telephone and did not immediately respond to a written inquiry on Monday.

China has reported three bird flu outbreaks in poultry over the past month. No human cases have been reported, but authorities warned Friday that one is inevitable if the country isn't able to prevent outbreaks in chickens and ducks.

In Australia, disaster and pandemic coordinators from the 21-member Asia-Pacific Economic Cooperation forum, along with health, animal and quarantine officials, were meeting behind closed doors to determine the best ways to deal with various threat levels posed by diseases such as bird flu.

Speaking on the sidelines of the meeting, Vietnamese Vice Minister of Agriculture Bui Ba Bong said the country needs $50 million and help building up its stockpile of bird flu drugs as it struggles to keep a lid on the virus.

Vietnam has been hardest hit by bird flu, which has killed more than 40 people in the country and prompted authorities to destroy tens of millions of poultry.