However, it was not clear whether the person who hijacked the Arkansas server was an actual al Qaeda terrorist or someone with other motivations.

Ken Dunham, malicious code manager for iDefense Inc., an Internet security firm based in Reston, said a growing number of computer crimes are being committed in the name of political causes, with some hackers seeking to identify themselves with terrorism in a bid to boost their importance in the hacker subculture.

Mansfield, who said she speaks fluent Arabic and has tracked Terrorist 007's activities since February, said the poster admitted online that he does not speak Arabic. His postings in Arabic bear signs of being run though an electronic translator, she said. She said the person has posted at least 900 items on the al Ansar Web site.

In a statement posted on the Northeast Intelligence Network's Web site yesterday, Mansfield described the poster as "a self-proclaimed U.S.-based terrorist."

In addition to the links to the Arkansas computer server, the al Ansar site featured downloadable copies of video depicting the beheading of American businessman Nicholas Berg, an al Qaeda-produced video called "Wills of Martyrs" and video of a deadly car bomb attack on a housing complex in Riyadh, the Saudi Arabian capital, Mansfield said.

The al Ansar site is a popular destination for al Qaeda sympathizers and is often one of the first places where videos of terrorist attacks and ultimatums are posted, Mansfield said.

James Lewis, a senior fellow at the Center for Strategic and International Studies, said that sites run by al Qaeda and its sympathizers change addresses often and rely on word of mouth for publicity.

He added that the practice of taking advantage of unsecured computer space to host information is a common tactic of al Qaeda backers.

Terrorist 007 apparently moved the same material to other locations on the Internet, Mansfield said. Earlier this year, a person identifying himself as Terrorist 007 posted similar material to an FTP server run by The George Washington University in Washington, D.C., Mansfield said.

University spokesman Matt Nehmer said security officials at the university had no knowledge of any such intrusion, and had not been contacted by law enforcement officials.