Two men have been killed after they stopped their vehicles on a highway to fight and were hit by a passing truck on the far north coast in New South Wales.

Emergency services were called to the accident on the Pacific Highway, south of Woodburn about 8:10pm last night.

The drivers stopped about 5km south of Woodburn and got out of their vehicles.

Witnesses have told police the men were fighting in the northbound lane when they were struck by a B-double being driven by a 35-year-old man from Albury.

Both men sustained critical injuries and died at the scene.

The driver of the truck was taken to Ballina Hospital where he has undergone mandatory blood and urine testing.

Police are still working to formally identify the two men killed.

The Pacific Highway has been reopened in both directions this morning and there are no delays to traffic in the area.