The outbreak was discovered on Monday at a farm with about 11,000 egg-laying chickens in Izumi City in Kagoshima prefecture in southwestern Japan, reported Reuters.

Several other outbreaks have been reported to the World Organization for Animal Health in Europe and Asia. It's a sign the virus is spreading quickly.

"The NA subtype of the highly pathogenic avian influenza virus was identified and it was confirmed to be H5N8 subtype," the ministry said.

The increase in the number of people around the world getting infected from avian influenza this year is becoming a source of concern for epidemiological experts, especially as the world slowly recovers from the current health crisis.

China has reported 21 human infections with the H5N6 subtype of avian influenza in 2021 to the World Health Organization, compared with only five last year, it said, with six dead and many of the others critically ill.

In February, Russia registered the first case of the H5N8 strain being passed to humans from birds and reported the matter to the WHO. There was no sign at the time of transmission between humans.

Japan temporarily suspended exports of chicken meat and eggs from all regions earlier this month after reporting the first outbreak, though the ministry has said the consumption of those items, if infected, pose no risk to humans.

Last winter, Japan had its worst season of winter flu on farms yet, with almost 10 million chickens culled and more than a third of the country's prefectures affected.

Japan has an egg-laying flock of around 181 million hens and a broiler population of 140 million, according to the ministry of agriculture.