TOKYO: Tests have confirmed that bird flu detected in chickens in southern Japan was the virulent H5N1 strain that has caused more than 160 human deaths worldwide, the Japanese Agriculture Ministry said yesterday.

The virus, identified by the National Institute of Animal Health, killed about 4,000 chickens last week at a farm in Kiyotake town in Miyazaki prefecture (state).

The institute is still running tests for DNA analysis and more pathogenic details of the virus, including its strength, the ministry said in a statement.

Miyazaki, about 900 km southwest of Tokyo, is Japan's largest chicken producing region.

Officials on Monday burned all the dead birds and culled the 8,000 surviving chickens at the farm. Authorities also banned the shipment of eggs and chickens at 16 farms within a 10-km radius of the affected farm, where local authorities were to take further disinfectant measures yesterday.

The Agriculture Ministry also ordered a nationwide inspection of poultry farms to detect any signs of sick birds, and environment officials began a national survey to look into the possibility that a bird flu virus might have been brought by migratory birds.

Since 2003, the H5N1 bird flu strain has killed at least 161 people worldwide, according to the World Health Organization.

Bird flu was found in Japan in 2004 for the first time in decades. There has been one confirmed human case involving the H5N1 virus in Japan, but no reported human deaths.

Adding to regional worries, a senior Thai agriculture official said on Monday that 1,900 ducks had been culled in the northern province of Phitsanulok after some of the birds had tested positive for H5N1.

In Vietnam, the virus appeared to be spreading fast among fowl in the country's southern Mekong Delta, the major rice-growing region.

Source: China Daily/agencies