A United Airlines flight to Italy was forced to return to the US after a passenger’s laptop dropped through the cabin into the aircraft's cargo hold.

Flight UA126 from Washington Dulles to Rome Fiumicino, returned to Virginia on 15 October due to a safety risk posed by the lost laptop, which contained a lithium-ion battery.

According to FlightAware data, the United Boeing 767 took off at around 10.22pm local time and was almost an hour into its eight-hour journey when the pilots reported a problem.

The laptop was turned on and fell “behind a cabin wall panel and through a small gap leading to the cargo hold”, where it could not be accessed, said the airline.

Lithium-ion batteries are a risk on planes, as a damaged, overheated, or defective battery can uncontrollably heat up and cause a fire.

As the object contained a lithium battery and was in a part of the cargo hold without a fire suppression system, it was deemed a safety risk by the crew.

An air traffic control recording of the incident, per You Can See ATC, hears the pilot request to turn around as a precaution due to a “minor situation with a passenger who has somehow dropped a laptop that was on, down the sidewall into the cargo pit area of the aircraft.”

He adds, “We can’t access it, we can't see it, so our decision is to return to Dulles and find this laptop before we can continue over the ocean.”

“That’s a new debrief story. I’ve never heard anything like that before”, replied air traffic control.

The aircraft made a u-turn off the coast of Boston and landed safely back at Washington Dulles airport just over two hours after it first departed.

Following a three-hour delay to locate the laptop and refuel, the United flight departed to continue its journey to Rome.

An airline spokesperson told The Independent: “On October 15, United flight 126 safely returned to Dulles International Airport as a precaution to retrieve a customer’s laptop that had fallen behind a cabin wall panel and through a small gap leading to the cargo hold. Maintenance crews retrieved the laptop, inspected the aircraft and the flight later departed for Rome.” (The Independent)