A key Islamic rights group is demanding an immediate inquiry after six Muslim imams were removed from a US flight.
The imams deny reports thaT they refused to leave the flight
The six men were taken off the US Airways flight, bound to Phoenix from Minneapolis, after a passenger reported "suspicious activity" to cabin crew.
The men were told to disembark shortly after saying evening prayers. Three of the six had stood as they prayed.
The scholars, who were returning from a conference, allege they were handcuffed and "humiliated" during the ordeal.
They were questioned by police, they said, for several hours.
A spokeswoman for US Airways said concerns about the group had been raised by a passenger, who had passed a note to a flight attendant.
She added that police were called after the men refused to get off the flight when asked to do so by the captain and airport security workers.
The men deny that they refused to leave the plane and other reports that they chanted "Allah" while being escorted off, according to the Council on American-Islamic Relations (CAIR).
The advocacy group said it was determined to establish whether the incident was the result of "anti-Muslim hysteria by the passengers and/or the airline crew".
"Unfortunately, this is a growing problem of singling out Muslims or people perceived to be Muslim at airports," said CAIR spokesman Ibrahim Hooper.
He also alleged that US Airways had refused to put the men on another flight after they were questioned.
According to CAIR, the men had been at a conference of the North American Imams' Federation, which had also been attended by Keith Ellison, a Minneapolis Democrat who has just become the first Muslim elected to Congress.