South Korea imposed on Monday a 12-hour lockdown on poultry farms in three provinces to curb a spreading bird flu outbreak, banning the movement of animals, people and vehicles.
More than 640,000 poultry have already been slaughtered since the outbreak was first detected on January 16 at a duck farm in Gochang, 300 kilometres southwest of Seoul.
The H5N8 strain of bird flu has since been identified in 17 other farms, with tests being carried out in 22 others, and a further 810,000 poultry have been identified for slaughter.
The 12-hour travel ban on poultry farmers and other members of the industry, including vets, took effect at 6am Monday in Gyeonggi province - which surrounds Seoul - and the provinces of South and North Chungcheong.
The South Korean capital was not included in the lockdown.
During the 12-hour period, local officials will oversee disinfection operations at all farms in the region.