The number of Web sites offering step-by-step instructions on carrying out suicide attacks, deploying poison gas, and setting off cell-phone detonated bombs, among other terror tactics, have soared in the past year, according to a report released yesterday by the Simon Wiesenthal Center.

There also has been a surge in the number of online games promoting racism, anti-Semitism, and terrorism; streamed videos of staged executions, including beheadings in Iraq, and sites that encourage young Muslim men to join terrorist groups like Al Qaeda, according to the eighth annual study, called Digital Terrorism + Hate.

“The Internet has emerged as a virtual online university of terrorism,” the associate dean of the center’s Museum of Tolerance, Rabbi Abraham Cooper, told The New York Sun.

Rabbi Cooper said 20% to 25% of the 6,000 bigoted or violent sites referenced in the study were explicitly terrorist-related, marking a major jump since last year, when such sites accounted for only a tiny portion of those logged. “Al Qaeda affiliates and those who think like them have embraced every aspect of technology to entice young people into a culture of death,” Rabbi Cooper said.

He estimated that about four-fifths of terrorism-related sites are published in Arabic.

The center’s senior researcher, Rick Eaton, who has been studying the proliferation of hate materials for two decades, said that while many sites have become more technologically sophisticated, even their more amateur counterparts can attract thousands of visitors a month. Mr. Eaton and his research team, who linked about two dozen sites to divisions of Al Qaeda, were tipped off to many of the sites through online discussion groups. Tips related to forthcoming attacks are immediately passed on to law enforcement officials, he said.