More than 350 people who have committed crimes or are suspected of terrorist links have been arrested in a federal crackdown on foreigners with visa violations, part of a broader effort to prevent Al Qaeda (search) from disrupting U.S. elections.

Agents with U.S. Immigration and Customs Enforcement (search), a Homeland Security Department component known as ICE, are matching identities of visa violators nationwide with names on secret government terrorism databases in hopes of finding al-Qaida operatives.

"We're intensifying it in the days leading up to the election," ICE spokesman Dean Boyd said Friday.

Some groups representing Muslims and Arab-Americans are concerned some people may be targeted because of their ethnicity or religious beliefs.

"If somebody breaks the law in terms of their immigration status, they should pay the price," said Ibrahim Hooper, spokesman for the Council on American-Islamic Relations. "We can only hope they are not targeting people based on whether they are Muslim."

Since its inception in June 2003, ICE's Compliance Enforcement Unit has opened more than 5,200 investigations of visa violators nationwide. Of those apprehended, 359 are considered "priority arrests" — those with possible links to terrorism or known criminal histories.

The stepped-up initiative is one of many government efforts given new urgency by persistent intelligence indicating Al Qaeda is determined to attack inside the United States before the Nov. 2 election.

The FBI has conducted more than 13,000 interviews this year in an effort to gather intelligence about the potential plot, with more to come.

Special attention is being paid to the hunt for immigration violators because some hijackers involved in the Sept. 11, 2001, terror attacks (search) had violated terms of their visas.

One was Hani Hanjour, who never showed up for English classes as required by his December 2000 visa. About nine months later, he piloted American Airlines Flight 77 into the Pentagon.

In its final report, the Sept. 11 commission said the government could have "potentially excluded, removed or come into further contact with several hijackers" if a better immigration tracking system had then existed.

Since the attacks, the government has created several systems for tracking foreigners with visas. They can alert agents to possible violators, such as students who drop out of school and business people who don't do the work they promised when they arrived.

Advocates for Muslims and Arab-Americans don't fault the government for pursuing people in the United States illegally. But they say the FBI and ICE efforts, taken together, are triggering renewed fears that U.S. counterterrorism officials are targeting people based on their religion or ethnic or national origin.

The American-Arab Anti-Discrimination Committee said in a statement that it had been contacted by ICE officials after raising concerns that the initiative "will be selectively carried out against Muslims and Arabs." Even after those talks, the group said it remained worried ICE would base many of its investigations on a government registry of men from 24 mostly Muslim and Arab countries.

Advocacy groups also raised concerns about the FBI interviews. They say agents appear to be targeting some people multiple times.

Justice Department officials acknowledge the FBI is talking to people who have been helpful in the past but also to many others when they gain new information about them.

ICE officials insist their investigations are triggered only by alleged visa violations, not by a person's ethnicity, religion or national origin. Priority is given to "high-risk" violators whose names appear to match any of those compiled by the government's Terrorist Screening Center (search), a new FBI-run operation to consolidate U.S. lists of suspected terrorists and sympathizers.

"These are not mass roundups. It's very case-by-case and specific. It isn't targeting any specific race or religion," said Boyd, the ICE spokesman.

Specific examples given by ICE of recent arrests include:

—A 32-year-old Jordanian, arrested after overstaying a visa, was living in an apartment in which agents found literature involving terrorist affiliations and Internet web sites. Deportation procedures are continuing.

—A 27-year-old Azerbaijani, attending a Maryland college, was arrested and deported after making violent threats against fellow students.

—A 22-year-old Pakistani who didn't maintain his status as a college student in Oklahoma was found to have a loaded firearm, which is a violation for an illegal alien. He was deported.