Last year, Japan confirmed the first outbreak of swine flu in 26 years in the country. The fever was found in a farm in the Gifu Prefecture, central Japan.

The fever detected in Japan is a different strain from the deadly African swine fever that China has been battling, Japan's agriculture ministry has previously said.

The disease found in Gifu is also known as hog cholera. It occurs among pigs, wild boar and is not infectious for humans.

Japan is the world's 10th largest pork producer, and exports about 12 billion yen ($A161 million) worth of pork products annually.

Pork prices in China, the world's top consumer of the meat, have hit a record after an epidemic of African swine fever swept through the country's pig herd, killing millions.