TOKYO : The Japanese farm ministry has confirmed that the latest bird flu outbreak, the nation's fourth case this year, was caused by the virulent H5N1 strain of the virus.

The National Institute of Animal Health confirmed the strain of the virus that caused the outbreak in the past week at a poultry farm in the town of Shintomicho in Miyazaki prefecture on the southern island of Kyushu, according to a brief agriculture ministry statement.

Authorities have already ordered the killing of 93,000 chickens on the farm, where more than 80 chickens had died suddenly, prompting the investigation.

Two H5N1 cases were detected last month in Miyazaki prefecture and a third case of bird flu was confirmed in Okayama prefecture in the west of Japan's main island of Honshu.

H5N1 has killed around 160 people across the world since late 2003 and it is believed it can be transmitted through contact with infected birds' waste.

Health officials have warned that if the disease mutated into a form easily transmissible by humans, it could cause a pandemic with the potential to kill millions of people.

Japan confirmed an outbreak of the H5N1 strain of bird flu in January 2004. Since then, the nation has seen several further outbreaks of the H5N1 strain as well as the H5N2 virus.

- AFP/ir