Dusseldorf  - The Japanese school in Dusseldorf has been closed following an outbreak of swine flu which has infected 30 pupils, officials in the west German city said Thursday.

Most of the cases were not severe, but two of the children were seriously ill, said Heiko Schneider, head of the Dusseldorf Health Office.

All the affected students have been placed in quarantine at home, Schneider said.

He said the number of infections was expected to rise because other children had complained of flu symptoms.

Some 560 students attend the school, which will remain closed until the end of next week, school authorities said.

It was not clear how the outbreak started.

Dusseldorf, located in the populous state of North Rhine-Westphalia, has the largest Japanese community in Germany.

Latest figures by the World Health Organization show that 74 countries have reported 27,737 cases of infection, including 141 deaths.

Most of the cases, and nearly all the deaths, were in North America.

In Europe, the most affected countries are Britain with 666 cases and Spain with 331. (dpa)