HAZMAT crews are mopping up a spill on the NSW north coast after a petrol tanker collided with a car.

Police said the petrol tanker and car collided head-on on the highway north of Ballina shortly after 3pm (AEDT).

The car driver was flown by rescue helicopter to Lismore Base Hospital with serious injuries.

The truck driver has been taken to Ballina Hospital with non-life threatening injuries.

The crash caused one of the truck's tanks to rupture, and hazmat crews are trying to limit the amount fuel leaking onto the road.

The highway is expected to be closed for several hours and motorists are being asked to postpone travel if possible.