Japan has found a new case of bird flu in a region neighbouring Tokyo, but the strain is unlikely to be the virulent type that has been blamed for dozens of deaths in Asia, a local government official said on Thursday.

Several chickens on a farm in Saitama prefecture, west of the capital, tested positive for the H5 type of bird flu, but studies are still being made to determine the subtype.

"We will have to wait for the final results to be certain, but it is unlikely to be the virulent strain of bird flu," an official with the Saitama prefectural government said.

He said the strain was likely to be the same as that reported earlier this year, which was the weak H5N2 strain.

Early last year, Japan reported its first outbreak of avian flu in 79 years when it discovered chickens infected with the virulent H5N1 strain.

That strain first surfaced in poultry in Hong Kong and China eight years ago and is known to have killed more than 50 people in countries such as Vietnam, Thailand and Cambodia.

In late June, Japan reported a case of the H5N2 strain of bird flu in Ibaraki prefecture, northeast of Tokyo.

Several other farms in the neighbourhood later also reported cases of the same strain. Following guidelines, all 98,300 chickens on the farm in Saitama will be slaughtered, and restrictions will be placed on the movement of eggs and chickens in a 5-kilometre (3.107 miles) radius around the farm to prevent the virus from spreading.