TOKYO — Japanese youngsters are getting so wrapped up in Internet-linking cell phones that the government is starting to advise parents and schools to limit their use among children.

The government is worried that elementary and junior high school students are getting victimized by cyberspace crimes, are spending long hours exchanging mobile e-mail and are overusing cell phones in negative ways, Masaharu Kuba, a government official overseeing the initiative, said this week.

"Japanese parents are giving cell phones to their children without giving it enough thought," he said. "In Japan, cell phones have become an expensive toy."

The warning recommendation made by an education reform panel was submitted to Prime Minister Yasuo Fukuda's administration, and was approved this week.

The panel is also asking Japanese makers to develop cell phones with only the phone-call function and GPS location-finding (which can be a safety feature for children).

About a third of Japanese sixth-graders have cell phones, and 60 percent of ninth-graders have them, according to the education ministry.

Most mobile phones in Japan are sophisticated gadgets offering high-speed Internet access called 3G, for "third-generation."

But the panel said better filtering programming is needed for Internet access to protect children.

Some youngsters are spending hours at night on e-mail with their friends.

One fad is "the 30-minute rule," in which a child who doesn't respond to e-mail within half an hour gets targeted and picked on by schoolmates.

Some youngsters have become victims of Internet crimes. In one case, children sent in their snapshots to a Web site and ended up getting threatened for money, Kuba said.

Cell phones tend to be more personal tools than computers. So parents find that what their children are doing with the phones is increasingly difficult to monitor, Kuba said.

Some Japanese children commute long distances by trains and buses to school and parents rely on cell phones to keep in touch with their children.

Parents typically pay about 4,000 yen ($39) a month in cell phone fees for each child.

Japan boasts a relatively low crime rate compared to other industrialized nations, but some people are concerned that the Internet could be exploited for serious crimes.