Earlier: A bus fire near Bulli Pass partially closed the M1 Princes Motorway Monday morning.

The fire caused adjoining bushland to catch alight just before 11am. Both blazes were extinguished by fire crews about 11.30am.

Traffic is heavy on the M1 Princes Motorway with one southbound lane closed as the salvage effort takes place.

The bus driver was the only person on board the bus at the time of the fire and evacuated safely, a NSW Ambulance spokesman said.

Diversions via Bulli Pass and the Princes Highway have been lifted.

Emergency services and Roads and Maritime Service crews remain at the scene.

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