Updated

Several dozen Iraqis in the United States believed to pose a wartime threat will be detained by the FBI using new powers to arrest people on immigration violations ordered by Attorney General John Ashcroft.

The order took effect Feb. 28, the last day the Immigration and Naturalization Service and its enforcement laws fell under Justice Department jurisdiction. The INS ceased to exist the next day, when it was folded into the Homeland Security Department.

Ashcroft's decision, confirmed Wednesday by two law enforcement officials who spoke on condition of anonymity, gives more than 11,000 FBI agents and several thousand marshals new arrest powers. Previously, that authority was reserved for INS agents, some Customs agents and 35 police officers in South Florida under a program promoted by Ashcroft.

The FBI investigates major crimes and gathers domestic intelligence. The Marshals Service mainly tracks down and transports fugitives.

The law enforcement officials described the move as crucial in the fight against terrorism. Immigration charges frequently are used to initially detain suspected terrorists or sympathizers while other charges are developed.

The officials said it makes little sense for the FBI to delay arresting potential terrorists or spies while waiting for an immigration officer to show up.

One Justice Department official said the powers would be used "only in appropriate situations, such as when the public safety requires prompt action."

The Iraqis expected to be detained have been under surveillance by the FBI and are believed to be sympathetic to President Saddam Hussein. Those who would be detained are in violation of U.S. immigration laws, mostly because of expired visas, the officials said.

With the opening stages of the U.S. war against Iraq under way, the FBI will move to arrest the Iraqis rather then keeping them under surveillance. Officials said the Iraqis, who are not known to pose any imminent or specific threat, are living in Miami, Detroit, New York, Washington and possibly other cities.

The expansion of FBI authority comes as the bureau conducts voluntary interviews with up to 50,000 Iraqis living in this country, both to identify potential terrorists and spies and to provide assurances that any instances of hate crime will be investigated vigorously.

FBI agents also have been holding public meetings with Muslim groups and have said repeatedly the intent of the voluntary interviews is not to arrest people for immigration violations such as an expired visa.

The latest Justice Department directive appears to directly contradict that policy, said Dalia Hashad of the American Civil Liberties Union.

"This is clearly a community that is terrorized by and terrified of the government," said Hashad, the ACLU's advocate for Arabs, Muslims and people from South Asia. "Every time this community extends a hand, it has been slapped."

Justice Department officials maintained that the FBI's new powers would not be brought to bear on these voluntary interviews or Muslim outreach programs. They said the FBI did not get power to initiate immigration investigations or deport people; that authority lies with the Homeland Security Department.

The ACLU and Muslim groups have been highly critical of several government antiterrorism efforts. These include the forced registration of thousands of mostly Muslim men and boys with U.S. immigration authorities and the FBI's tallying of mosques as one way to determine investigative priorities in local areas.

In addition, the U.S. government will detain anyone from 33 countries where terrorism has a presence, including Iraq, who seek to claim asylum in the United States on grounds of political persecution. Those people previously were freed pending the outcome of their asylum claims.

Also Wednesday, the FBI said in its weekly bulletin to 18,000 state and local law enforcement agencies that police should watch closely for any suspicious activity by vehicles carrying Iraqi diplomatic license plates. These plates, issued by the State Department, are distinguished by the letters TSD after the numbers.

The vehicles are attached to the Iraqi mission to the United Nations in New York and to an Iraqi office in Washington. They can only be driven in the five boroughs of New York City and a 25-mile radius of downtown Washington unless permission to go elsewhere is granted by the State Department.