Japan on Wednesday started checking poultry farms near a household in Oita Prefecture where an outbreak of bird flu was confirmed Tuesday, Kyodo News reported.

A sanitation worker who had come into contact with the infected chickens had developed a slight fever but tests showed he does not have flu, the news agency said.

On Tuesday, Japan confirmed that 13 bantams kept by the household in the town of Kokonoe in the prefecture were confirmed to have had the bird flu virus.

The household kept the 13 bantams along with a duck. Seven of the bantams were found dead between Saturday and Monday and the six others and the duck were killed for testing. It is not yet known whether the duck was infected.

The prefectural government began inspecting poultry farms within a 30-kilometer radius of the household. There are about 50 poultry farms within the radius, which keep a total of 570,000 chickens for egg production and 760,000 broiler chickens.

Households which keep chickens or other birds as pets or for other purposes will also be checked by sanitary inspectors.

On Tuesday, the Japanese government ordered residents and poultry farmers within a 30-km radius of the household in Kokonue not to move chickens or eggs outside the area. The radius covers parts of Oita and Kumamoto prefectures.

The Ministry of Agriculture, Forestry and Fisheries also said Tuesday it has banned public access to the area and begun sterilizing chicken coops.

The ministry said the virus found in the latest outbreak is of the H5 type, but further analysis is needed to confirm whether it is the H5N1 strain that has been hitting other parts of Asia.

It is the second outbreak of avian flu in Japan this year. The ministry found Japan's first case of avian flu in 79 years in Yamaguchi Prefecture on Jan. 12. About 34,000 chickens were slaughtered in the Yamaguchi case.