A MAN has died after his sedan collided with a semi-trailer near Ballina in northern NSW.

Police say the truck driver was not injured in the crash, which happened about 3.45am (AEDT) today, but he will have mandatory blood and urine tests.

Southbound lanes on the Pacific Highway remained blocked on Saturday morning, with traffic diverted onto the Old Pacific Highway through Ballina.

Meanwhile, a man has died following a head-on collision between two cars north of Canberra.