KOBE, JAPAN (AFP) - Hundreds of Japanese students whose schools have been closed this week to contain a swine flu outbreak have instead flocked to karaoke parlours with their friends, club operators said.

Authorities in and around Osaka and Kobe cities have shut more than 4,000 schools, kindergartens and colleges after the first swine flu cases were confirmed Saturday and the number of infected reached 178 by Tuesday.

Tens of thousands of students have been asked to stay away from schools and avoid leaving home if possible - but many teenagers are clearly bored.

"About 10 different groups of high school students came here yesterday," a karaoke club manager in Osaka, Yoshikatsu Ishida, told AFP.

He said he declined to accept the young customers when he found they were supposed to stay at home while their schools were closed.

Another karaoke club manager said: "We suddenly had a number of high school students after 2:00 pm yesterday, right after the announcement that schools would close for a week."

"All of our karaoke rooms were full at one point, and I'm expecting something similar today," he said. "I don't have the right to say something like 'you should stay at home.'"

An Osaka prefecture official said: "We've asked schools to close down and let students stay at home unless there's a special need to go out."

Asked about the students' karaoke bar visits, he told AFP: "We'll observe the development ahead."