Police are appealing for dashcam footage after a fiery two-truck crash closed the M1 northbound south of Ballina for several hours this morning.

The highway has now reopened following the crash at Coolgardie, about 15km south of Ballina.

Emergency services rushed to the scene about 4.35am today (Thursday) after two trucks collided in the northbound lanes of the Pacific Highway.

One of the trucks burst into flames, but both drivers escaped without injury.

Fire and Rescue NSW and NSW Rural Fire Service crews tackled the blaze, with crews from Alstonville and Ballina among the first to arrive.

Firefighters contained the blaze to one prime mover and its A-train. They also contained a substantial diesel spill using absorbent material.

The fire completely destroyed the truck.

Police closed the northbound lanes while emergency crews extinguished the fire, investigators examined the scene and crews carried out a major clean-up.

The closure forced northbound traffic onto local roads through the Wardell area for several hours.

The M1 has since reopened to northbound traffic.

Richmond Police District officers are investigating what caused the collision.

Police want to hear from anyone who witnessed the crash or was travelling through the area at the time and has relevant dashcam or mobile phone footage.

Anyone with information can contact Ballina Police Station or Crime Stoppers on 1800 333 000.