The man, believed to be in his 50s, was taken to hospital after his motorbike collided with a Subaru Forrester at Pheasants Nest.

Police, ambulance, Fire and Rescue NSW and Rural Fire Service teams were called to the scene just after 2pm.

A man, believed to be in his 50s, was riding a motorbike in the southbound lanes of the highway when his motorbike and the car – driven by a 72-year-old woman – collided.

A NSW Ambulance spokesman confirmed the man was treated for a “critical arm injury” at the crash scene.

He was airlifted to Liverpool Hospital by a NSW Ambulance rescue helicopter in a serious condition.

The woman was treated for minor injuries and taken by road ambulance to Liverpool Hospital.

Witness reports suggest that shortly before the crash, a car was seen driving northbound in the southbound lanes of the highway.

A NSW Police Force spokesperson said the incident was currently under investigation by the Crash Investigation Unit.

Both southbound lanes of the highway were closed for several hours while investigation teams assessed the scene. Motorists were diverted off the highway at Picton Road, where traffic was diverted along the Old Hume Highway and Remembrance Drive to return to the highway at Bargo.