TOKYO, Dec. 5 (Xinhua) -- An outbreak of swine flu has been found at a public research institute in the central Japan city of Minokamo, in Gifu Prefecture, the local government said Wednesday.

Following two pigs testing positive for the virus, also known as hog cholera, the prefecture began the culling of hogs at the institute, which breeds around 500 pigs for premium pork products.

Japan's farm minister Takamori Yoshikawa said at a meeting in response to the outbreak Wednesday that, "It is extremely serious that the infection was detected at the prefectural institute. It will have a huge impact."

At the same meeting, Gifu Governor Hajime Furuta apologized for the incident occurring at a facility that should have been better protected.

"We are really sorry that the outbreak occurred at the prefectural facility, which is supposed to have well-prepared preventive measures," Furuta was quoted as saying.

The latest outbreak of hog cholera marks the third case in Japan since an outbreak was reported earlier in the year. Prior to that, Japan had not seen a case of swine flu for decades.

This year's cases have all occurred in Gifu Prefecture, with the first outbreak occurring at a pig farm in September and the second at a public livestock center park in November.

Following the outbreak on September 9, 546 hogs were culled and buried and pork exports from across Japan had to be halted to contain the spread of the virus.

The local government in Gifu has suggested the virus may have made its way onto the farms and facilities by way of wild boars or pigs that had contracted the disease and passed it onto the local farms and enclosures.

No infections of pig cholera have been recorded in Japan since the first outbreak in 1992 and the virus was declared eradicated in 2007, according to official records.