Japan has confirmed its second outbreak of bird flu, dashing hopes that the country was now free of the virus.
The bird flu outbreak has hit the poultry industry across Asia
The farm ministry said chickens at a farm in Oita prefecture on southern Kyushu island had died from avian flu.
It is not yet known if they died from the H5N1 virus - the strain that has killed 20 people in Asia.
In Thailand, the virus has reappeared in eight provinces where mass culls had been carried out and has also broken out in a new province.
Thailand had hoped to declare the country free of bird flu by the end of the month, but the virus has now been found among fighting cocks in areas where mass culls had been carried out.
Six people have died from the virus in Thailand, while 14 people have died in Vietnam, the only other country where the virus has spread to humans.
The United Nation's Food and Agriculture Organisation (FAO) said Thailand had been premature in its optimism, warning that the outbreak could last for several months.
AVIAN FLU ALERT
First jumped "species barrier" from bird to human in 1997
In humans, symptoms include fever, sore throat, and cough
Types which threaten humans are influenza A subtypes H5N1 and H9N2
"You cannot expect, seeing the extent of the outbreaks you had, that with one go of stamping it out you have resolved the problem," the FAO's regional animal health officer Hans Wagner told AFP news agency.
"You have to expect that you get secondary outbreaks or new outbreaks."
In Japan, officials had been preparing to declare the country free of bird flu on Thursday if there were no new cases.
Until Tuesday, Japan's only confirmed case of avian flu this year was on a farm in the prefecture of Yamaguchi, at the southern end of the main island of Honshu.
On Monday, Vietnam confirmed another human case.
Tens of millions of chickens and ducks have already been slaughtered across Asia as the outbreak has also hit China, South Korea, Cambodia, Taiwan, Indonesia, Pakistan, Laos and Japan.
So far there is no proof that the virus can pass from human to human.
Health experts are worried that if the virus mixes with a regular human influenza strain, it might create a mutant form that was able to pass between humans, triggering a human flu pandemic.