Air Canada said it is investigating an incident where a passenger on a flight from Toronto to Dubai opened the cabin door before takeoff and fell onto Pearson Airport runway, resulting in injury.

In a statement sent to local media, Air Canada said the incident occurred on flight AC056 yesterday, Monday, while the plane was waiting at the departure gate.

According to the airline, the passenger who boarded the plane did not go to their seat, but went and opened the cabin door on the other side of the plane.

Air Canada said the passenger was injured after falling onto the runway.

Emergency services and police attended the scene.

The flight, which was scheduled to carry 319 passengers, was delayed but departed later.

Air Canada said: "We can confirm that all approved boarding and cabin operation procedures were followed."

It is not clear what prompted the passenger to open the cabin door.

Air Canada said it continues to "review the incident."