More than 160 passengers and crew were on board the United Airlines jet
A Qatari diplomat has been freed from custody in the US after allegedly sparking a bomb scare on a plane.
Two F-16 jets were scrambled to intercept the United Airlines plane, on a flight from Washington to Denver.
Reports said Mohammed al-Madadi, 27, had smoked in a toilet and then joked about setting fire to his shoes. No explosives were found.
US officials close to the case told news agencies it was likely Mr Madadi would leave the country.
They said the US would not declare the diplomat, who has immunity from prosecution, "persona non grata".
However, one official told Agence France-Presse news agency: "His ability to function effectively has been significantly compromised."
The state department's official statement, from spokesman Philip Crowley, was: "We are satisfied with the seriousness by which they (Qatar) take what has occurred. That's why we have confidence that this will be resolved very quickly."
Mr Madadi, the embassy's third secretary, was released by the US authorities after being questioned, according to a statement by Brown Lloyd James, a law firm representing the Qatari embassy.
Unnamed US officials told Associated Press that Mr Madadi was on his way to attend a prison meeting with jailed al-Qaeda member, Ali al-Marri, at the time.
Investigators were told that Mr Madadi was asked about the smell of smoke in the toilet and he made a joke that he had been trying to light his shoes - an apparent reference to the 2001 "shoe bomber" Richard Reid, AP news agency reported.
Reid, a British citizen, tried to blow up a transatlantic jet carrying 197 passengers with explosives hidden in his footwear.
In a statement, Qatar's ambassador to the US, Ali Bin Fahad al-Hajri, said the diplomat "was certainly not engaged in any threatening activity", and "facts will reveal that this was all a mistake".
The plane, with more than 160 passengers and crew on board, arrived at Denver International Airport from Washington's Reagan airport.
The crew had asked for the flight to be met on the ground by police, officials said.
The incident came just months after a Nigerian man allegedly tried to detonate a bomb on a passenger jet arriving in the US.
Umar Farouk Abdulmutallab, 23, was overpowered by passengers and crew shortly before the Northwest Airlines plane landed in Detroit from Amsterdam on 25 December. He has been charged with attempting to destroy a plane.