Japan's agriculture ministry is planning to revise its guidelines on vaccinating pigs to prevent the spread of swine fever.
The virus has spread to eight prefectures since an infection was confirmed in Gifu Prefecture, central Japan, in September of last year. That was the country's first case in 26 years.
Earlier this month, swine fever was also detected in pig farms in Saitama and Nagano prefectures.
Sources say the agriculture ministry will determine on its own when and where to vaccinate pigs.
The ministry is planning to ask for the approval of political parties and then seek experts' opinions.
Some are strongly opposed to the vaccinations out of concern over their possible impact on distribution and exports.
But pig farmers across the country are stepping up their calls for vaccinations, as efforts to catch wild boars, which are thought to be carrying the virus, have not been effective so far.
Vaccinations for swine fever were conducted until 2006 in Japan.
Ministry officials say that eating pork from vaccinated pigs poses no health risks.