Three excavators and several heavy vehicles worth almost $1 million, which were being used to build the Hunter Expressway, were destroyed by a suspicious fire last night.
About 8.40pm police and firefighters were called to Buchanan, near Averys Lane, where two excavators were ablaze and a third had already been destroyed by the fire.
The fires took several hours to extinguish safely, because diesel was fuelling the flames.
A number of heavy vehicles parked at the construction site were damaged by the fire.
Police said the fire appeared to be deliberately lit.
Anyone who saw suspicious activity in the vicinity is urged to contact Crime Stoppers on 1800 333 000.