Twelve passengers on a Northwest Airlines flight that returned to Amsterdam?s Schiphol airport after the pilot raised an alert over worrying behavior have been arrested, airport police said.?Twelve passengers were arrested. We cannot give more details,? spokesman Rob Stenacker told reporters.

The arrests were carried out ?after questioning and in accordance with information provided by the crew?, he added, however.

The plane was flying from the Dutch capital to Mumbai, India, with 149 passengers on board when what the pilot called ?behavior of concern? prompted him to return to Amsterdam.

The jet, which was flying over Germany at the time, was escorted back to Amsterdam by two Dutch air force jets as soon as it entered Dutch air space.?Flight 42 from Amsterdam to Mumbai with 149 passengers returned back to Amsterdam when a couple of passengers displayed behavior of concern,? Northwest Airlines said in a statement released in the United States.?Northwest is cooperating with the appropriate government officials. Flight 42 is cancelled for today, but will be traveling to Mumbai tomorrow. Passengers are being accommodated at local hotels,? the company added.

A police spokesman at Schiphol airport said earlier: ?A certain number of passengers are being heard as witnesses to get a clearer picture of what happened.?

The National Coordinator for Counterterrorism said there was no reason to upgrade the country?s terrorism alert level, the Dutch ANP news agency said.

Muslim group alarmed over reports of US racial profiling

■ A leading US Muslim group said it was disturbed by reports that US authorities were racially profiling passengers at New York?s Kennedy airport. The Council on American-Islamic Relations said it had received three separate reports from Iraqi-born Americans alleging they were detained for up to six hours at the airport last week without justification. The allegations came from a Michigan couple, two people from California and a New Jersey woman travelling with her five children. The council said that it feared hundreds of other passengers had been filtered by security on the basis of their names or appearance. It called on officials ?to partner with the American Muslim community in order to ensure national security in a manner that is consistent with American values of justice and equality.? A statement from US customs authorities denied they were screening passengers on the basis of ethnicity, but acknowledged increased security over an alleged plot by Muslim extremists to bomb US flights from Britain. ?CBP (Customs and Border Protection) does not use racial profiling, however CBP officers may scrutinise more closely individuals arriving from high-risk countries,? it said in a statement. It refused to divulge why some passengers were screened, citing privacy issues, but acknowledged that there were ?extremely long wait times? at Kennedy airport on the day concerned, saying heightened security was mainly to blame.