UPDATE 1.10pm: FIREFIGHTERS worked to contain a diesel spill following the B-double truck rollover this morning.

Macksville Fire and Rescue NSW Captain David Brunsdon said on arrival firefighters found a B-double on its side and estimated 250-300 litres of diesel spilled onto the road.

Fire and Rescue NSW Mid North Coast Inspector Tony Lenthall said firefighters absorbed as much diesel as possible but some had entered drainage.

Mr Lenthall said absorbent booms had been placed outside of drains to prevent diesel from entering the Nambucca River. 

ORIGINAL 10am: ANOTHER truck has crashed on a "very notorious" stretch of the Pacific Highway this morning.

The truck crashed at the entrance of the Macksville Bridge and no other vehicles were involved.

Macksville Police Sergeant Belinda Dalzell said the B-double truck, driven by an interstate driver, rolled on the highway at about 1am.

Sgt Dalzell said the cause of the crash was still under investigation.

The truck blocked traffic for hours.

Sgt Dalzell said a one-lane contra-flow was opened at 4.30am. Traffic has since eased.

It is understood the truck was carrying a load of steel and spilled diesel on the highway.

Sgt Dalzell said that stretch of highway was a "very notorious" section and had a number of crashes.

A NSW Ambulance Media spokeswoman said there were no indications the male driver had been injured.

The driver was taken to Coffs Harbour Base Hospital by ambulance.