* Coal train derailed near Hunter Valley in New South Wales
* Hunter Valley is Australia's top thermal coal-producing region
* Yancoal says its Moolarben Coal operations directly impacted
* 3rd Australian freight train derailment in as many months (Adds comment from Australian rail safety regulator in paragraphs 5-7)
By Melanie Burton
MELBOURNE, Feb 7 (Reuters) - Australian coal haulier Pacific National said on Thursday that one of its trains derailed near the Hunter Valley in New South Wales and that some services would be affected while repair work was carried out.
The Hunter Valley is Australia's top thermal coal-producing region and home to operations run by Yancoal YAL.AX , Glencore GLEN. and Peabody Energy BTU.N .
There were no injuries, Pacific National said by email, adding that the train had derailed in the early morning on Wednesday near the area of Baerami with the last six wagons coming off the tracks.
"The regulator is currently onsite assessing the situation with the removal of the wagons and repairs to the track expected to commence after assessments have been completed," the company said.
The derailment is the third involving a freight train in as many months. Australia's rail safety regulator said each incident involved unique circumstances and cautioned against trying to link them.
"The rate of freight train derailments in Australia in recent years has remained steady at between 0.4 and 0.5 derailments per million freight train kilometres," the Office of the National Rail Safety Regulator told Reuters in an email.
It said it was working with industry to drive the figure lower.
Pacific National said rail services west of Mount Pleasant would be impacted while the work is being done.
The Australian Transport Safety Bureau said it was investigating the incident that caused damage to around 2 km (1.3 miles) of the train track.
The train had been travelling through a section of the network that was under a temporary speed restriction of 20 km per hour (13 miles per hour), which had been imposed to "mitigate risk due to a measured series of defects in the track," the bureau said in a statement on its website.
A Yancoal spokesman said that its Moolarben Coal complex had been directly impacted by the train derailment but that it was too early to advise of any potential impact to customers, as it awaited confirmation of when haulage would restart.
A Glencore spokesman referred Reuters to Pacific National. Representatives from Peabody were not immediately available to comment.
In November, BHP Group BHP.AX forced a train off its tracks after it ran away without its driver en route to the northwestern iron ore export hub of Port Hedland. following month, around 30 wagons in an empty iron ore train derailed around 700 km (438 miles) east of Perth after poor weather eroded part of the track.