It took 100 firefighters hours to bring a roadside inferno under control after a fuel tanker burst into flames on the side of a motorway near Wollongong.
The truck was carrying 36,000 litres of fuel along the M1 Princes Motorway west of Wollongong when it caught fire before 9am on Friday.
About 20 emergency crews converged on the scene to douse the flaming vehicle with foam, a Fire and Rescue NSW spokeswoman told AAP.
The 44-year-old male driver, the only occupant of the truck, was able to escape unharmed as homes around the fire were evacuated.
Crews battled to keep the blaze within containment lines as the fireball repeatedly flared up, with fuel spilling onto the roadway and into drains.
Firefighters by midday had achieved a "significant fire knockdown", FRNSW posted on Twitter.
Acting Superintendent Kevin McNeil said it was potentially a "very dangerous situation" on a major roadway busy with school holiday traffic.
"A fuel tanker full of fuel could have caused extreme damage," he told reporters in Wollongong.
The fire appeared to have started in the truck's cabin but it's unlikely the driver will be charged, Supt McNeil said.
"We're investigating the matter at the moment but it is unlikely anything the driver has done has caused this fire."
Hazmat crews are expected to remain on the scene to help decant the remaining fuel from the vehicle and keep it from flowing into drains.
The M1's northbound lanes reopened on Friday afternoon with a reduced speed limit of 60km/h.
The southbound lanes will remain closed overnight as emergency services work to clean up the area.
Images posted on social media show massive flames erupting from the tanker parked on the side of the road.
© AAP 2019