The number of domestic infections cases of influenza A/H1N1 in Japan hit 92 as of Monday morning with all the patients in Osaka and Hyogo prefectures, local media reported.

The total number of the infection in the country now stands at 96, including the first four cases contracted in North America.

The country is now facing the risk of grass-root outbreak which could lead the WHO to raise its new flu pandemic alert from the current 5 to the highest level of 6, which means community-level outbreaks in two different WHO regions, experts has warned.

The WHO is launching investigation on the situation in Japan.

The Japanese government will convene an emergency meeting to discuss countermeasures on the spread of the epidemic.

The newly confirmed domestic cases included high school students, college students, their family members and teachers, the health ministry and local governments said Sunday.

Japan on Saturday confirmed the first eight cases of domestic infection on students of a Kobe high school. The later confirmed cases in Osaka are said to have contacted the Kobe students in a volleyball match. Osaka and Hyogo are adjacent in the Kansai region.

All of the newly confirmed patients had no record of overseas travel.

Meanwhile, a total of 143 students at the Kansai Okura Senior High School where many infections in Osaka were found, have shown symptoms of influenza since around Monday and are feared to be infected, according to local media reports.

The privately run school said it will be closed from Monday through Saturday.

More than 1,000 educational facilities -- kindergartens, and elementary, junior and senior high schools -- in Osaka and Hyogo prefectures have decided to suspend classes for certain periods following the confirmation of new flu infections in the prefectures, Kyodo News reported.

The two prefectures have requested private schools to follow suit.

Osaka Gov. Toru Hashimoto convened a meeting of a new flu task force on Sunday and decided to ask facilities such as movie theaters to suspend operations to prevent the spread of the flu.

TV clips showed people in Kansai region started to wear masks in public spaces and rushed to drug stores for buying medicines.

The Japanese government on Saturday shifted the stage of its new-flu action program from "a period of overseas outbreak" to "an early period of domestic outbreak" and called for companies and schools in the areas concerned to allow individuals to avoid commuting during rush hours.

The Kyodo News quoted Masato Tashiro, a member of the World Health Organization's emergency committee, as saying that several hundred people in Japan already may have been infected with the new flu.