DOZENS of South Korean schools have cancelled classes as officials scrambled to quell fears that rain contained radioactive material from Japan's stricken nuclear plant.

More than 130 primary schools and kindergartens in Gyeonggi province surrounding the capital Seoul cancelled or cut classes today after rain began falling on orders from the provincial education office.

An office spokesman called it part of "preemptive measures for the safety of students".

The office had told schools on Wednesday to cancel or shorten classes due to "growing anxiety among students and parents over conflicting claims on the safety of radiation exposure".

Schools in remote areas, where students have a long walk to class, were particularly encouraged to cancel activities. At schools which stayed open, teachers were advised to suspend outdoor activities.

Complaints from parents mounted on the website of Seoul city's education office, which refused to cancel classes and called for a calm response to the fears.

"Please order class cancellation. I'm worried to death about my kid and can't sleep," said one posting.

Education authorities in North Chungcheong province south of Gyeonggi postponed football, baseball and other sporting events.

Concern grew in the nation closest to Japan after the weather agency said on Monday that radioactive material from the crippled Fukushima nuclear plant may be carried to the peninsula by south-easterly winds.

The amount of radioactive material contained in the rainfall is too tiny to pose any health threat, the prime minister's office said today, calling for education offices to refrain from "making parents nervous".

Originally published as S Korea schools shut over radioactive rain