A Pakistani man who police said appears on a terrorist watch list was arrested late Sunday on criminal charges after a traffic stop in Baltimore County.

Muhammad Asif Haider, 27, of New York was detained in connection with an indictment issued against him last week in the Southern District of New York, federal officials said. The indictment accuses Haider, who it says is also known as Asif Iqbal, and others of trafficking in fraudulent immigration documents.

Federal prosecutors and FBI officials declined to say yesterday why Haider might have been on a terrorist watch list or even to confirm the assertion by police that he was on such a list.

Sgt. Vickie Warehime of the Baltimore County police department said Haider was a passenger in a vehicle that was stopped on Reisterstown Road shortly before 10:45 p.m. The driver could not produce a driver's license, Warehime said, and a check of the two passengers matched Haider to the watch list.

Warehime said the check showed more than Haider being wanted in connection with the indictment in New York. "It's above and beyond that," she said. "It's a special category that alerts law enforcement to potential terrorist involvement."

Haider is scheduled to appear this morning in U.S. District Court in Baltimore. Calls to his federal public defender were not returned yesterday.

Barry Maddox, an FBI spokesman in Baltimore, said no information links Haider to Mahmud Faruq Brent, a Baltimore resident charged last week with conspiring to support a terrorist organization.

The indictment says Haider and others sold fraudulent green cards or Social Security cards to an undercover New York police officer and at least one confidential informant.

Haider was in the country illegally, according to an Immigration and Customs Enforcement official. The agency lodged a detainer with authorities in Baltimore County to ensure that he is not released.