The Japanese agriculture ministry on Thursday confirmed that the virus detected in the second case in a month of birds' mass death in Miyazaki Prefecture is the highly virulent H5 strain of the bird flu virus.

The result was based on a test by the National Institute of Animal Health in Tsukuba, Ibaraki Prefecture, which will further analyze the virus sample to determine if it was the lethal H5N1 type, Kyodo News reported.

About 1,300 birds died in mass from Monday to Wednesday at a farm in the city of Hyuga. It was the second bird flu case in a month in the prefecture and the sixth in Japan since 2004.

Earlier this month, a farm in the town of Kiyotake, 60 kilometers away from Hyuga, saw 3,500 of its birds killed by the H5N1 strain of bird flu and had all of its 12,000 birds incinerated.

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.