(CNN) -- A Qatari diplomat who was questioned by federal investigators after a disturbance on a flight to Colorado has been released without charges, officials said Thursday.

Mohammed al-Madadi was en route to Colorado for a series of consular visits, including a visit with a convicted terrorist being held in a federal facility in Florence, Colorado, a spokeswoman for the Qatari Embassy told CNN. His flight was escorted into Denver, Colorado, by two F-16 fighter jets after initial reports that he may have attempted to set a shoe on fire -- a report that may have stemmed from what one U.S. official called an "unfortunate comment" by the diplomat.

The U.S. official told CNN the passenger was in a lavatory for a long time and may have been smoking. He was questioned by air marshals aboard the United Airlines jet and again by the FBI after the plane landed.

Alison Bradley, a spokeswoman for the Brown Lloyd James public relations firm, told CNN that al-Madadi has "been given clearance to travel back to Washington," and a federal law enforcement official told CNN he will not face charges.

Bradley, whose firm represents the Qatari government, said al-Madadi was on official business and planned to meet with college students from the emirate while in Colorado. In addition, he had arranged a consular visit with Ali al-Marri, a Qatari citizen who is serving an eight-year prison term for conspiring to provide material support to a terrorist organization.

Al-Marri had been held in U.S. military custody for six years before pleading guilty to charges in a federal court in Illinois in 2009. He was sentenced in October and transferred to Florence in March.

International law allows prisoners serving time in another country to receive visits from representatives of their home country's embassy, "and all civilized states regularly exercise this responsibility to send diplomatic representatives to visit their citizens incarcerated in other countries," Bradley said in a statement to CNN.

And the Qatari ambassador to the United States, Ali Bin Fahad al-Hajri, said in a statement posted on the embassy's Web site that al-Madadi "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," he said.

Fran Townsend, who was a homeland security official in President George W. Bush's administration, told CNN the incident may 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.

Townsend said that law enforcement responded swiftly and efficiently. "The system worked as we would have hoped it would," she said.

Denver's airport remained open during the incident, according to a statement from airport officials.

One of the passengers on the flight was James Graybeal, director of public affairs for the North American Aerospace Defense Command, which oversees U.S. and Canadian air defenses. Graybeal said he was not aware of the incident until after the plane landed.

Janet Napolitano, the secretary of homeland security, commended federal air marshals who "swiftly responded to a potential threat to passenger safety while the plane was in flight."

"These highly trained individuals took appropriate and immediate action to secure the aircraft and communicate the potential threat to authorities on the ground -- ensuring that the flight was met by [Transportation Security Administration] and law enforcement officials when it landed safely in Denver."

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 came 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 after the December 25 bombing attempt, that subjected virtually all travelers from 14 predominantly Muslim countries to additional screening.

CNN's Jim Spellman, Jeanne Meserve, Carol Cratty, Paul Courson and Barbara Starr contributed to this report.