The government Wednesday decided to establish a task force of specialists to prevent computer vandalism by hackers and make a manual at an early date. The decision was made at a meeting of section chiefs from all ministries and government agencies in charge of computer-related issues. Earlier in the day, the Science and Technology Agency's Web site was hacked for the second time this week, Chief Cabinet Secretary Mikio Aoki said. The second attack was carried out using methods similar to the first attack, officials said. The agency discovered new alterations to the site Wednesday morning after information from the public about the previous incident was passed on to the agency by police, Aoki said. Wednesday's incident was the fourth breach of a government Web site since Monday. "We are investigating the incidents with the police," Aoki said at a news conference. "Government officials will hold a meeting on information security in the afternoon to discuss ways to deal with the attacks." Science Agency officials said a message in English and Chinese had been put on the Web site, which has been showing an "out of order" sign since the first attack. The message, accusing the Japanese government of denying the Nanking Massacre, was similar to the one found Tuesday on the Management and Coordination Agency's Web site, the officials said. The agency canceled access to the site shortly after discovering the unauthorized changes. On Monday, the Science Agency discovered a message written in English on its site that said in part, "Japanese are losers." A link connecting its site to a pornographic Web site overseas had also been inserted. The Metropolitan Police Department launched an investigation into the hacking Tuesday, when the first attack was discovered. "Investigations have been in progress to clarify the causes," Aoki told a news conference. Aoki said the Web sites of other agencies, including the Defense Agency and the National Police Agency, have not been affected.