Within hours of the terrorist attacks last month, the word was out: Israel was responsible for crashing airplanes into the World Trade Center and the Pentagon. The reason? Its intelligence agency, Mossad, wanted to discredit Arab Muslims. The "evidence": 4,000 Israeli employees in the World Trade Center were said to be absent the day of the attacks because they had been tipped off.

This notion at first seemed to be the province of a small number of bin Laden allies. For instance, Muhammad Atta's father blamed the Israelis for the attacks during a press conference last month and called the United States the "root of terrorism.

" But in the month since the attacks, the rumor has spread, starting in Pakistan and the Mideast, moving throughout the World Wide Web and ending up in educated Muslim communities in the United States.Last week it was revealed that Salam Al-Marayati, a respected American Muslim leader prominent in national efforts to promote interfaith dialogue, said in an interview on a Los Angeles radio talk show that Israel should be on the "suspect list" of those who carried out the attacks. A few days later, another scandal emerged: Imam Mohammed Gemeaha of New York's prominent Islamic Cultural Center had fled to Cairo, where he gave an interview in Arabic stating that "Jews planned those terrorist attacks."

These comments by reputable religious leaders were milder versions of what is appearing by the thousands on web message boards. Thousands of message board posts have appeared on all sorts of sites, from the most moderate to the most strictly Muslim. Some writers seem angry, but most explain their views in calm terms, as if they are simply stating a fact that others have somehow, unfortunately, missed.

On Iviews, an American Islamic news site, a member named AB writes: "I now strongly believe that the Jews knew about the attack and its plans, and most probably helped a great deal in the 'penetration' of the US intelligence, and caused for the suicide attack to occur successfully."

A post on the Islamic Circle of North America's website is also typical: "Zionists want to see that Muslims and Arabs are attacked and their properties burned down so that the environment of the Spanish Inquisition days are recreated in the 21st century United States, so that Muslims either leave Islam for their own security or are murdered or exiled."

Beliefnet member Jihaad wrote something similar, though he toned down the rhetoric: "I believe that... Israel is indirectly connected to our recent tragic events. Sure, Jews will attack me for this, but I believe that Israel's Mossad possibly had evidence that this attack would happen."

It can be dangerous to extrapolate from Web message board posts to broad generalizations. But experts believe a significant number of American Muslims do harbor anti-Israel views because of the Middle East conflict and that those views sometimes slip into anti-Semitic feeling.

Michael Sells, an expert on Islam at Haverford College, says anti-Jewish rhetoric in the "classic European sense with the myth of Jews as Christ-killers" was imported into the Middle East and is now moving into American Muslim circles. "People in the Middle East know that the Israeli lobby in the U.S. is one of the most powerful," Sells says. "So it's not hard to understand why they would slip into the conspiracy view that Jews control the world. But it's unacceptable in a religious leader, or anyone who's educated, and certainly anyone in the United States."

On the Islamic Circle of North America website, a vigorous discussion about the subject is going on under the heading Israel is the devil. At another place on the site, a user named Mujahid Suleiman Solano writes: "If the USA can keep the Zionists down, I am sure we 'peaceful Muslims' will be able to keep the dogs back."

Where did this rumor come from? Apparently, shortly after the attacks, a prominent Taliban cleric named Israr Ahmed started flooding mosques and Islamic centers in the United States with faxes that read: "The secret Israeli service Musad [sic] orchestrated these terrorist attacks ... [which] are a vital link in the chain of events that the Jews are undertaking to fulfill their dream of world domination." The rumor then spread to Syrian Defense Minister Mustafa Tlass, who blamed the attacks on the Mossad. It became commonly accepted in Pakistan and ,the Middle East, and from there the rumor spread to the United States, often with the help of email and the Web.