TOKYO, Nov 30, 2010 (AFP) - Japan began slaughtering about 23,000 chickens Tuesday at a poultry farm in western Shimane prefecture where an outbreak of bird flu was discovered, the local government said.

The local government of the prefecture, 600 kilometres (about 370 miles) west of Tokyo, started killing the 23,300 birds at the farm where five chickens were found dead Monday, local officials said.

Preliminary tests confirmed that the chickens had died of the H5 subtype of the avian flu virus, the officials said.

In an effort to prevent a larger outbreak, the local government decided to slaughter all the chickens at the farm while setting up nine checkpoints for disinfection and banned any movement of chickens within 10 kilometres.