Austria's stricter immigration controls are jeopardizing classes at the Japanese School in Vienna, as two teachers failed to obtain visas before their visa-free stays in the country expired Saturday.

The school, which has six other full-time teachers dispatched from Japan and a few locally hired part-time teachers, said it will try to cope by asking the remaining staff to cover more lessons while looking for students' parents with teacher's licenses who can help.

Two teachers who arrived in Austria last spring had been working under the bilateral visa exemption arrangements permitting stays of up to six months while waiting for long-term visas to be issued.

Austria has tightened rules for issuing visas for all foreigners this year amid rising unemployment and growing complaints over generous measures to protect refugees.

Since spring, immigration authorities have necessitated foreigners to take out Austria public insurance, which costs 200-300 euros per month for a family of a Japanese school teacher.

But as that insurance takes six months to become effective after being obtained, the authorities also have required foreigners to buy private insurance to cover the blank period.

That means a Japanese teacher's family must pay up to 1,300 euros monthly for insurance, which proved too expensive for the two teachers who consequently failed to obtain visas before the expiration of their visa-free stays.