Federal agents yesterday swarmed into an Islamic institute in Northern Virginia that has been the target of a joint U.S.-Saudi crackdown over allegations that it promoted an intolerant brand of Islam.

Dozens of FBI, customs and Internal Revenue Service agents participated in the morning raid on the Fairfax County-based Institute for Islamic and Arabic Sciences, law enforcement sources said. The number of agents attracted the notice of neighbors and TV crews, who recorded the event.

Federal officials would not comment on the raid or say whether it was part of a broader investigation of the institute, a "distance learning" center that teaches Arabic and Islamic studies and that until recently was sponsored by the Saudi Embassy. But the Saudi government revoked its sponsorship in December after examining allegations that the school promoted a form of Islam that is intolerant of other strains of the religion as well as Christianity and Judaism.

The State Department later revoked diplomatic visas of 11 people affiliated with the institute. They were among several dozen Saudi personnel whose diplomatic credentials were revoked as part of an effort by both countries to curb extremist Islamic teachings in the United States.

Institute officials did not return calls yesterday. But Arsalan Iftikhar, legal director for the District-based Council on American-Islamic Relations, or CAIR, said an institute staff member called CAIR attorneys while the raid was underway. "They said they had no idea what was going on,'' said Iftikhar, who went to the scene and talked with agents from the FBI and U.S. Immigration and Customs Enforcement. "They said everyone in the building was interviewed but was allowed to leave. No one was arrested or detained.''

Ibrahim Hooper, a CAIR spokesman, said the local Muslim community is concerned that the raid is a "fishing expedition by the government.''

But Ali Al-Ahmed, head of the District-based Saudi Institute and a critic of the Institute for Islamic and Arabic Sciences, said it teaches a "militant" brand of Islam. "In my mind, if this organization keeps running in this country, it will create a lot of Osama bin Ladens,'' he said. "The crux of their message is that this is a Christian-Jewish land and that we should hate those people.''

Michael Petruzzello, whose public relations firm represents the Saudi Embassy, said agents took computers in the raid and interviewed institute staff members. He said the diplomatic credentials of the 11 institute clerics and instructors accredited by the Saudi Embassy were withdrawn in December. U.S. officials are examining the visa status of the six remaining staff members, who are not Saudi, he said.

Riyadh has increased cooperation with Washington in the war on terrorism since Saudi Arabia was hit in May by the first of two deadly suicide bombings.