The U.S. Commission on Civil Rights informed government agencies on Friday that they will be closely watched for violations of laws banning racial or ethnic discrimination.

The commission held a briefing to explore whether civil liberties are being trampled as the federal government seeks to find those responsible for the Sept. 11 terrorist attacks and protect Americans from future tragedies.

Concerns centered around reports that commercial pilots have removed some passengers who were viewed as security risks based on the fact that they appeared to be Middle Eastern. Additional concerns involved reports that many of those detained in the government's investigation are being held without bail, some on minor immigration violations.

James Zogby, president of the Arab American Institute, said his organization has documented 11 incidents involving 20 people who appeared to be Middle Eastern or Muslim and were either removed from planes or not allowed to board.

Commissioners said they plan to monitor whether government agencies are using racial profiling to try to identify terrorists entering the country or catch potential airplane hijackers.

The commission plans to collect data on how immigration cases are handled by the Immigration and Naturalization Service and how the U.S. Department of Transportation investigates discrimination complaints from travelers.

More than 600 people have been detained or arrested in the government's investigation into the attacks, including about 150 who are being processed for immigration violations.

After hearing that some defense attorneys have been unable to find detained clients, the INS sent a formal reminder to its staff that all have a right to have representation, general counsel Owen Cooper said.

Samuel Podberesky, assistant general counsel for enforcement at the Department of Transportation, said the department is vigorously investigating such complaints. Although the law does allow pilots to remove passengers who pose a safety risk, he said, it outlaws making those decisions solely on the basis of race or ethnicity.

The Associated Press contributed to this report.