UPDATE: A LEARNER pilot and his instructor have been killed when their plane crashed in a paddock south of Lismore in northern NSW.

The two men died about 10.15am.

Police said their next of kin haven't been informed yet.

The aircraft burst into flames on impact at the property, off the Bruxner Highway in South Gundurimba, south of Lismore.

"There is a large debris field of about 50m in length," said a Fire and Rescue NSW spokesman.

"Crews are applying foam to the remains of the plane."

Crime scene investigators are to attend the scene, about 2km from Lismore Airport.

The cause of the crash is not yet known.