Education boards in 17 of Japan's 47 prefectures have increased the ratio of teachers to first-year pupils in elementary schools to combat the widely feared breakdown of classroom discipline, a Kyodo News survey showed Sunday.

Education boards in the 11 prefectures increased teachers per class, while the remaining six reduced the number of pupils in the classroom to about 30.

The moves are in response to the so-called "classroom collapse" phenomenon, which usually affects large classes numbering 40 children or more. The Education, Culture, Sports, Science and Technology Ministry loosened guidelines on class sizes this month, which marks the beginning of the school year.

The new guidelines allow local education boards in the 47 prefectures and 12 designated cities to set limits on class size. Thus, some classes may have 30 or fewer students.

The cities of Chiba and Hiroshima have also decided to assign more than one teacher to first-year elementary school classes that have 36 or more pupils. The city of Nagoya reduced some class sizes in elementary schools to 30 or fewer pupils.

Yamaguchi Prefecture's education board has also launched a new system on a trial basis for sixth-year pupils in some elementary schools under which some school staff teach a particular subject to several classes. Normally in Japanese elementary schools, one teacher takes care of almost all subjects.