In this file photo dated Nov 29, 2016, health officials investigate a chicken farm in Sekikawa village, Niigata prefecture, northern Japan, after a highly contagious avian flu strain in poultry was detected. (PHOTO / KYODO NEWS VIA AP)

TOKYO - Central Japan on Friday started culling about 50,000 birds after the region confirmed the first highly pathogenic avian influenza outbreak during the autumn and winter season this year, according to the Ministry of Agriculture, Forestry, and Fisheries of Japan.

A highly pathogenic avian influenza outbreak, the sixth reported case in Japan, has been confirmed on a farm housing about 50,000 chickens in the city of Yamagata in Gifu prefecture, after local authorities received reports on Thursday of an increased mortality rate among chickens at the farm, prompting swift action, based on the ministry's press release on Friday.

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The preventive operation of culling all 50,000 birds on the affected farm started on Friday and is expected to conclude by Saturday, while the transportation of poultry and egg products within a 10 km radius of the outbreak's epicenter from the affected farm to areas outside the designated zone was restricted.

Approximately 158,000 birds across 25 poultry farms within this restricted zone will be subject to limitations on movement and transportation.

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The bird flu season in Japan typically begins in October each year.