China and Vietnam have reported major new bird flu outbreaks, as Japan moved to cull 180,000 chickens at a farm where signs of the virus were found.
There are fears of further outbreaks in China
The lethal H5N1 virus killed nearly 9,000 chickens in China's Liaoning province and 3,000 birds in Bac Giang province in Vietnam, officials said.
Japanese officials said tests showed 80 chickens in Ibaraki had been exposed in the past to a virus from the H5 family.
But the chickens had survived, and no active virus was found.
Further tests are needed to identify its exact strain.
The H5N1 virus has killed millions of birds across Asia, and millions more have been culled in an effort to stem the spread of the virus.
At least 60 people have also died of the disease, since its resurgence at the end of 2003. There are fears the virus could mutate into a form that passes easily between people.
China's new outbreak - the fourth in three weeks - occurred on 26 October, the agriculture ministry said in a report posted on the website of the World Organisation for Animal Health.
More than 300,000 birds in the area around the village of Badaohao have been culled as a precaution.
H5N1 BIRD FLU VIRUS
Principally an avian disease, first seen in humans in Hong Kong in 1997
Almost all human cases thought to be contracted from birds
Possible cases of human-to-human transmission in Hong Kong, Thailand and Vietnam, but none confirmed
Earlier outbreaks hit the provinces of Hunan, Inner Mongolia and Anhui, but so far China has seen no human bird flu infections.
The latest report came despite Beijing's efforts to tighten control on the country's vast poultry flocks, and vaccinate millions of birds.
The report said the virus had also killed 20 magpies and other wild birds in the village of Badaohao.
In Vietnam, bird flu has killed poultry in Bac Giang's communities of Yen Lu, Van Trung and also Tang Tien, the animal health official said.
He added that the areas had been put under quarantine.
Tests are now being conducted for at least one suspected human case, reports say.
The Japanese cases were found on a farm in Ibaraki prefecture, north-east of Tokyo.
Antibody tests on 80 chickens at the farm showed they had all been exposed at some time in the past to a bird flu virus from the H5 family, the prefecture authorities said in a statement.
It was the first time in more than a year that bird flu had been detected in Japan. Many of the earlier cases were found to be the H5N2 strain, which is no threat to humans.
"There is little concern that the virus is the H5N1 type, which is infectious to human beings, because there has been no case of H5N1 in this area," an agriculture ministry official told the French news agency AFP.
BIRD FLU OUTBREAKS IN 2005 (H5N1 STRAIN)
The H5N1 strain remained largely in South-East Asia until this summer, when Russia and Kazakhstan both reported outbreaks
Scientists fear it may be carried by migrating birds to Europe and Africa but say it is hard to prove a direct link with bird migration
EU has banned the import of captive live birds