CHISAKI WATANABE of Associated Press in Tokyo

Japan announced a crackdown on Thursday on internet sites that spread information on group suicides, bomb-making and other crimes following a homemade explosive attack by a high school student.

Officials will step up monitoring of suspicious sites, urge schools and public offices to install internet filtering software, and establish criteria for service providers to disclose information they find on planned suicides, the government said.

“There has been harmful information on the internet, such as how to make bombs or soliciting group suicide,” said Chief Cabinet Secretary Hiroyuki Hosoda.

The measures, compiled by a task force formed in February, follow a surge in group suicides by people meeting on the Internet. Last year, 55 people killed themselves after meeting on the web, up from 34 the previous year, the National Police Agency says.

The announcement also comes after the arrest earlier this month of an 18-year-old boy accused of throwing a homemade bomb into a classroom. The explosion sprayed the room with glass and wounded 58 students.

Media reports said the boy was suspected of learning how to make the bomb from internet sites.

Officials have expressed concern about other crimes allegedly arranged over the internet, such as drug sales.

Tokyo plans to develop filtering software for mobile phones, which are used by many people in Japan to access the internet, the government said.

The government has been providing filtering software for computers free of charge since 1997 to block adult sites and other sites deemed harmful.

Hosoda said the new measures were not intended to violate freedom of speech and expression, and acknowledged it would be difficult to police the internet.