Rio Tinto has received grant from the New South Wales (NSW) planning assessment commission for vital development consent modification for the Mount Thorley Warkworth coal mine in Hunter Valley.

The approval will enable Rio Tinto to commence mining a small parcel of land within the original, larger expansion proposal as well as expands the mine in New South Wales, Australia.

The final decision on the proposed larger expansion for the mine lies with NSW Supreme court.

Mount Thorley Warkworth mine, which has been in operation for 30 years, supplies international and domestic markets with up to ten million tonnes of semi-soft coking coal and thermal coal per annum.

Once approved, the company will extend the mine 15km south-west of Singleton, further west and south-west, extending its life expectancy to 2031.

Rio Tinto Coal Australia managing director Chris Salisbury said that the approval provides a Mount Thorley Warkworth mine with short-term lifeline and its more than 1300 workers.

The court overturned the state government’s approval last year for the expansion of the project, owned by Rio’s subsidiary Coal & Allied, citing environmental and social concerns.

"We’ve now been granted this short-term approval to resume operating as normal, but the disruption we’ve already experienced means coal production will fall by around a million tonnes this year and cost close to $100 million," Salisbury added.

"It is now absolutely critical that we gain a longer-term approval without delay, that allows us to maintain production levels at Mount Thorley Warkworth beyond 2015."