Ghassan Hanna served the FBI agents tea, and answered their questions while his 1 1/2-year-old daughter slept on his shoulder.

Another man was awakened by a loud knock at his door. Still another couldn’t believe the casually dressed man and woman were federal agents, and asked for another look at their badges.

Thousands of Iraqi immigrants are being questioned this week by FBI agents. FBI director Robert Mueller and other officials said Thursday that the interviews had yielded valuable information about possible targets for U.S. troops in Iraq, including descriptions of bunkers, tunnel systems and Iraqi military officials, among other material.

Agents also are trying to get information about possible terrorists, and reassuring Iraqis that the agency won’t tolerate hate crimes, the FBI has said.

While individual experiences have varied, advocates, lawyers and those interviewed say agents have been mostly polite and — at times — even friendly. Still, that doesn’t mean all their visits have been welcome. Some have used their interviews to chide agents for singling out Iraqis.

During some sessions, which have lasted from 15 minutes to more than an hour, agents have read from a list of questions.

They asked about people’s immigration status, their lives in Iraq, why they left, if they attend a mosque, the names of family members and whether they knew of any terrorists in the United States. Men and women, American citizens and recent immigrants, have all been interviewed.

When Mohammed Al-Jaibaji saw two agents, one wearing a ski jacket, walking up to his house last week, he thought they were salespeople. After double-checking their badges, Al-Jaibaji, 43, told them he left Iraq at age 18 to study at Kansas University.

“It didn’t bother me,” said Al-Jaibaji, a certified public accountant who lives in San Mateo, Calif. “They were very cordial and friendly. There was no sense of intimidation or interrogation.”

The two men in suits who showed up at Hanna’s Union City, Calif., home got an earful after asking what he thought of Saddam’s regime. Hanna left Iraq two weeks after Saddam came to power to escape a warrant for his arrest.

“I spent a good deal of time giving them a good history lesson, a good background,” said the 45-year-old engineer.