"(CNN) -- A passenger with diplomatic credentials of Qatar was detained Wednesday night after a disturbance aboard a United Airlines flight en route to Denver, Colorado, federal authorities said.
Initial reports were that the incident involved an attempt to set a shoe on fire, but there were later indications that the situation may have resulted from a misunderstanding.
The passenger was in a lavatory for a long time and may have been smoking, a U.S. official said. He also may have made an "unfortunate comment" referring to a shoe bomb when questioned on the plane, the official said.
Fran Townsend, a former homeland security official in President George W. Bush's administration, said that the person involved was a Qatar diplomat and that her sources said the incident may in fact have been a misunderstanding. She said law enforcement officials examined the man's shoes and were satisfied there were no explosives.
"The fear was that he would be Richard Reid-like," she said. Reid tried to light explosives hidden in his shoes on board American Airlines Flight 63 in December 2001. He is in prison after being convicted in a federal court.
Because of diplomatic immunity, it's unclear what charges, if any, the United passenger might face. He could be recalled to Qatar, Townsend said.
The Qatari ambassador to the United States, Ali Bin Fahad Al-Hajri, acknowledged the incident in a statement on his embassy's Web site by referring to reports of "a Qatari diplomat ... detained for suspicious behavior."
"We respect the necessity of special security precautions involving air travel, but this diplomat was traveling to Denver on official business on my instructions," the ambassador said in the statement, adding, "he was certainly not engaged in any threatening activity."
"The facts will reveal that this was a mistake, and we urge all concerned parties to avoid reckless judgments or speculation."
The statement did not name the diplomat.
Flight 663, a Boeing 757 carrying 157 passengers and six crew members, took off Wednesday evening from Reagan National Airport in Washington.
Two F-16 fighters responded to the incident and intercepted the United jet, escorting it to the Denver airport. It landed safely at approximately 6:50 p.m. (8:50 p.m. ET).
Crew members asked law enforcement officials to meet the plane, said United spokesman Mike Trevino. The FBI responded to the incident.
"The situation is under control," said one of the law enforcement officials, who spoke on condition of anonymity. The airport remained open during the incident, according to a statement from airport officials. "There has been no impact on flight operations, and there are no flight delays or cancellations," the statement said.
One of the passengers on the flight was James Graybeal, director of public affairs for the North American Aerospace Defense Command (NORAD). Graybeal told CNN's Barbara Starr that he was not aware of the incident on board until after the plane landed.
Townsend said that law enforcement agencies responded swiftly and efficiently.
"The system worked as we would have hoped it would," she said.
Last year, a Nigerian man was arrested for trying to set off explosives hidden in his underwear on a flight from Amsterdam, Netherlands, to Detroit, Michigan, on Christmas Day.
The United Airlines incident comes just days after U.S. officials revised screening procedures for passengers coming into the United States.
The plan retained existing "no fly" and selectee lists, as well as the random selection of some passengers for additional screening. But it scuttled a much-criticized program, implemented in the wake of the December 25 bombing attempt, that subjected virtually all travelers from 14 predominantly Muslim countries to additional screening."
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