CHICAGO — The publisher of a Chicago-based Arabic newspaper was arrested Wednesday on charges of secretly gathering information on Iraqi opposition figures as an agent of Saddam Hussein's intelligence service.

Khaled Abdel-Latif Dumeisi, 60, was charged based partly on a dossier seized in a Baghdad safehouse in April as U.S. troops moved in and Saddam's regime was crumbling, federal officials said.

Finding the dossier capped an FBI investigation of Dumeisi going back at least four years that drew on interviews with informants, including a former Iraqi intelligence officer, federal officials said.

According to an FBI affidavit, Dumeisi told unnamed informants that he received training in Baghdad on how to gather information and was paid $2,000 or $3,000 to monitor Iraqi opposition activities in America.

Dumeisi gathered information on one U.S.-based critic of Saddam's regime by using a pen containing a hidden microphone and camera, a device provided to him by intelligence agents, the affidavit said.

Dumeisi was not charged with espionage because he did not spy on the United States and officials said they do not think he was an officer of the Iraqi intelligence service.

But they said he reported to the intelligence service and violated U.S. law by acting as an unregistered agent of a foreign government and conspiring to do so. Agents of foreign governments are required to register with the Justice Department.

U.S. Attorney Patrick J. Fitzgerald described the charges as serious.

"Those who gather information in the United States about people living in America for the purpose of providing the information to hostile governments should understand that the FBI will pursue them vigorously and the government will bring charges in appropriate cases," Fitzgerald said.

Federal officials said the dossier detailing the activities of an agent code-named "Sirhan" was found in the safehouse by members of an Iraqi opposition group and turned over to the FBI. They allege Sirhan was Dumeisi's code name.

Federal officials said unnamed informants identified Dumeisi as having contact with Iraqi intelligence agents attached to Saddam's mission to the United Nations — including one who was expelled as a spy.

The tall, softspoken Dumeisi appeared at midafternoon before U.S. Magistrate Judge Edward A. Bobrick, who set July 17 for a bond hearing. Until then Dumeisi will be housed in the Metropolitan Correctional Center.