Reuters reports that these will be the sixth and seventh cases of the avian flu in western Kagawa prefecture and the biggest culling to be done at one time since the country's first bird flu outbreak in more than two years was found in the poultry this month, an official at the prefecture said.

Chickens at the two farms in Mitoyo city tested positive in a preliminary examination for avian influenza on Thursday 19 November, after the farms had notified the prefectural government of an increase in the number of dead chickens.

The local government said it has confirmed the infection was a highly pathogenic strain of H5 bird flu from genetic tests on Friday 20 November.

The prefecture has already culled about 460,000 chickens for the past four cases, the official said.

Japan's last outbreak of bird flu occurred in January 2018, when 91,000 chickens at a farm in Sanuki city, also in Kagawa prefecture, were culled due to the H5N6 strain of bird flu, according to the agriculture ministry.

Read more about this story here.