Investigations have begun into the derailment of a fully laden Pacific National coal train earlier this week.
The train was on its way from Xstrata's Ulan coal mine to Newcastle's ports when a broken axle is believed that have partially derailed the train, according to the Newcastle Herald.
It was originally believed that a 'foreign object' had caused the train to jump the tracks however the broken axle is now believed to be the culprit.
The incident occurred on the Ulan line, near Bengalla.
According to the ABC the derailment damaged five kilometres of rail, and forced the closure of the Ulan line.
This is the second time a coal train has been derailed in the space of a month.
In late August another coal train broke down in the Hunter Valley, was hit by two locomotives sent to aid it.
Late last year another Pacific National coal train suffered a broken axle, resulting in a serious derailment that forced nine wagons off the track.
Image: The Newcastle Herald