The police report listed the incident as "Security-Other," but some saw the detention of six imams at the airport here as a case of "Flying while Muslim" — the idea that Muslims come in for extra scrutiny when they fly.

The imams were removed from the flight to Phoenix on Monday night after three of them said their normal evening prayers in the terminal in Minneapolis-St. Paul International Airport before boarding, said Omar Shahin, president of the North American Imams Federation, who was one of the passengers removed. The passengers were among 150 imams who attended a federation meeting in Minneapolis.

"It's discrimination," Shahin said, calling for a boycott of US Airways.

It was just the latest incident in which passengers who were Muslim or, in some cases, just not Caucasian were removed from a flight for questioning. In August, a flight from Amsterdam to Mumbai was escorted back to the airport by F-16 fighters because a group of Indians on the plane had a large number of cell phones, notebook computers and hard drives, and refused to follow the crew's instructions.

"In this country, there was a time that Catholics were profiled, and they were stereotyped and discriminated [against], and Jewish people," said Dr. Shahid Athar, a professor at the Indiana University School of Medicine, who also writes and lectures on Muslim interaction in the West. "It looks like it is our turn now."

In the incident Monday, a passenger reported overhearing the imams criticize the U.S. in Iraq and speaking angrily near the gate. The men were interrogated by the FBI and the Secret Service. They had to fly a different airline out of town on Tuesday after US Airways refused to let them on any of its flights.

"Unfortunately, this is a growing problem of singling out Muslims or people perceived to be Muslims at airport, and it's one that we've been addressing for some time," said Ibrahim Hooper, a spokesman for the Council on American-Islamic Relations. The group planned to file a complaint over the incident, Hooper said.

Nihad Awad, executive director of the Council on American-Islamic Relations, said the group has been receiving more reports of profiling.

According to a police report, a US Airways manager said three of the men had one-way tickets and no checked baggage. Some of the men also asked for seat belt extensions even though a flight attendant told police she thought they didn't need them.

The police report said the flight's captain had already decided he wanted the men off the plane after the passenger passed him a note pointing out "suspicious Arabic men."

An airport police officer and a Federal Air Marshal agreed the combination of circumstances was suspicious, and eventually asked the men to leave the airplane, according to the police report. The report said they got off the plane without incident.

"The police came and take us off the plane in front of all the passengers in a very humiliating way," Shahin said. "I never felt bad in my life like yesterday. It was the worst moment in my life when I see six imams, six leaders in this community, humiliated."

The Department of Homeland Security's Office for Civil Rights and Civil Liberties said in a letter Tuesday it had opened an investigation. It also said the department will coordinate with other government agencies with the authority to review the conduct of airline and other government employees.

Shahin eventually booked flights on Northwest Airlines — to Phoenix for five of the imams from the Phoenix-Tempe area and to Los Angeles for the sixth, who was from Bakersfield, Calif.

"May Allah the God forgive everyone who did this," Shahin said before going through the security checkpoint on Tuesday in Minneapolis.

US Airways Group Inc. issued a statement saying it was interviewing crew members and ground workers to find out more about what happened.

"We are always concerned when passengers are inconvenienced and especially concerned when a situation occurs that causes customers to feel their dignity was compromised. We do not tolerate discrimination of any kind," the airline said.