Three of the world’s biggest airlines have admitted some of their planes have cameras installed on the backs of passenger seats.
American Airlines, United Airlines and Singapore Airlines have new seat-back entertainment systems that include cameras.
They could also be on planes used by other carriers.
Companies that make the entertainment systems are fitting them with cameras to offer passengers options such as seat-to-seat video conferencing, according to an American Airlines spokesman.
But American, United and Singapore all say they have never activated the cameras and have no plans to use them.
A passenger on a Singapore flight tweeted a photograph last week of the seat-back display, prompting other air travellers to voice concerns about their privacy at 30,000ft.
Vitaly Kamluk, who photographed the camera on his flight, suggested that carriers should cover the lenses with stickers and said it would be easy for airlines to monitor passengers with them.