Vietnam slaughtered thousands of birds in its two largest cities on Tuesday, while other Asian nations boosted efforts to halt the spread of deadly avian flu.
China vowed to vaccinate its entire stock of 14 billion poultry against bird flu, with the government promising to help pay for the process.
Britain said it believed an outbreak of H5N1 in a quarantine center last month was introduced by birds imported from Taiwan. It had previously blamed it on a parrot from South America, a region which has no reported cases of H5N1.
Officials in Vietnam were racing against time to meet the government's deadline of Tuesday for ending poultry raising in the capital Hanoi and in Ho Chi Minh City, the country's commercial hub and largest urban center.
Police, veterinarians and health workers, wearing masks and protective clothes, gathered at duck farms in Hoang Mai district on the edge of Hanoi where outbreaks were detected earlier.