TOKYO: Japan on Tuesday ordered the slaughter of some 37,000 chickens after the country's third bird flu outbreak in less than a month, prompting Hong Kong to ban imports from the latest affected region.

Tests confirmed the H5 strain of the virus at a farm in Yamaguchi prefecture on the southwestern tip of Japan's main Honshu island after its owner reported late Monday that several chickens had died suddenly, the farm ministry said.

Officials began the slaughter Tuesday and asked farms within a 10 kilometre (six mile) radius not to transport poultry outside the area.

On Monday the government ordered the slaughter of about 42,000 chickens at a poultry farm in Miyazaki prefecture in southern Kyushu.

Earlier this month, bird flu reports came from another Miyazaki poultry farm that led to the cull of 4,000 chickens — the first outbreak of bird flu at a Japanese farm since April.

Some strains of avian influenza are fatal for chickens and pose a health threat to humans, who can fall sick after handling infected poultry.

Hong Kong's Centre for Food Safety said Tuesday it has banned imports of poultry meat and products from Yamaguchi prefecture in response to the Japanese announcement.

More than 4,600 tonnes of frozen and chilled poultry meat, as well as 17.7 million eggs, were imported from Japan into Hong Kong between January and October this year, the centre said.

On Sunday, Hong Kong hospitals raised alert levels as a woman diagnosed with the potentially deadly H7N9 avian flu virus was in critical condition.

The 68-year-old woman was hospitalised on December 25 after returning from the southern Chinese city of Shenzhen almost two weeks earlier.

Ten people had previously been diagnosed with H7N9 in the southern Chinese city, including three who died.

The H5N1 strain of bird flu has killed more than 400 people, mainly in southeast Asia, since first appearing in 2003.

The H7N9 strain has claimed more than 170 lives since emerging in 2013.