Thirty-one chickens were killed by bird flu virus, according to the preliminary tests, said a local government official on Sunday.

However, he added more lab work is needed to determine whether the virus was the H5N1 strain, whose result will come out on Monday.

Sterilization work has begun in Takahashi, which locates over 500 km west of Tokyo, said Kohei Kurose. Neighboring farms have been asked to refrain from moving their chickens, he said.

According to a statement by the Ministry of Agriculture, Forestry and Fisheries, all the 12,000 birds at the farm will be slaughtered if the final tests come back positive.

Earlier this month, 3,500 birds on a farm in the town of Kiyotake were killed by avian flu.

Bird flu infections hit dozens of farms in central Japan's Ibaraki prefecture in 2005 and 2006, resulting in the killing of at least 5.8 million poultry.

Source: Xinhua