The couple say they were escorted off the flight by a federal marshal
An engaged couple on board a United Air flight to Costa Rica were removed over the weekend.
The couple, who said they were en route to get married, said a federal marshal had escorted them from the plane before take-off from Houston, Texas - a claim which United has denied.
In a statement, the airline said that neither a marshal nor other authorities were involved. According to United Air, the pair "repeatedly attempted to sit in upgraded seating which they did not purchase and they would not follow crew instructions to return to their assigned seats".
"They were asked to leave the plane by our staff and complied," the airline concluded.
A United spokeswoman said the airline offered the couple a discounted hotel rate for the night, and rebooked them on a Sunday morning flight.
But Michael Hohl and his fiancée, Amber Maxwell, told local media they tried to pay for upgraded seating and were denied, after finding another passenger sleeping across their seats when they were the last to board.
After moving within the economy cabin a few rows up, flight crew denied their request to pay a supplement for the seats, which United sells as "economy plus", and told them to move back to their original seats, Hohl said.
"We thought not a big deal, it's not like we are trying to jump up into a first-class seat," Hohl told KHOU. "We were simply in an economy row a few rows above our economy seat."
The airline is already under heavy scrutiny following video footage surfacing of its staff forcibly removing a passenger from an overbooked flight last week.
Dr. David Dao, the 69-year-old Vietnamese-American doctor who was seen in video being dragged off a United flight a week ago, will likely sue the airline, his attorney told the media last week.
After the incident triggered international outrage, United Chief Executive Oscar Munoz apologized to Dao, his family and its customers, saying the carrier would no longer use law enforcement officers to remove passengers from overbooked flights.