Growing conflict between Israeli and pro-Palestine computer hackers is in danger of spiralling out of control, the FBI has warned, leading to further email flooding and denial of service attacks. The FBI's National Infrastructure Protection Centre (NIPC) warns that the growing catalogue of hacks and counter-hacks targeting Middle Eastern sites may soon spread to targets outside the region. As conflict has grown on the streets in recent weeks, Israelis and pro-Palestine supporters have also taken their quarrel on to the Internet, in a feud being dubbed "e-Jihad". Various pro-Palestinian sites including those of Islamic political groups Hizbullah and Hamas were attacked earlier this month and defaced with political postings. These defacements sparked further attacks on Israeli sites in retribution. Other sites have, however, also been drawn in. One Middle Eastern news service, the Daily Star, which has reported on numerous Internet attacks, claimed Monday it has also become a target for pro-Israeli computer hackers. To compound the situation, hacking groups on both sides have rallied supporters to their online quarrel and have set up Internet services allowing them to take part in primitive email flooding and denial of service attacks. The FBI believes it is only a matter of time before sites outside the Middle East are dragged into the feud. It suggests that US sites may be the first to suffer. "Due to the credible threat of terrorist acts in the Middle East region, and the conduct of these web attacks, recipients should exercise increased vigilance to the possibility that US government and private sector Web sites may become potential targets," says the alert. The NIPC does not, however, identify specific sites as at-risk but says that administrators should be prepared to block email addresses in case of email flooding and limit ping flooding at border routers in order to stop denial of service strikes. "The NIPC recommends that recipients of this assessment remain vigilant to the possibility that there could be some spill-over activity," it says. Read more at Hackers To have your say online click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read what others have said.