An engaged couple were removed from a United Airlines flight to Costa Rica on Saturday, as the airline remained under scrutiny following outrage caused by a video last week of a passenger being forcibly removed from a flight.

According to the couple, who said they were en route to their wedding, a federal marshal had escorted them from the plane before takeoff from Houston, Texas, but United denied this on Sunday, saying in a statement that neither a marshal nor other authorities was involved.

The couple "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," United said in a statement, adding "They were asked to leave the plane by our staff and complied."