MELBOURNE (REUTERS) - Korea Electric Power Corp's Bylong coal project was rejected by a state commission in New South Wales on Wednesday (Sept 18), marking a third coal project in Australia knocked back this year that cited climate change concerns.

In a 146-page document, the New South Wales Independent Planning Commission ruled the Bylong project was not in the public interest, partly because it was contrary to the principles inter-generational equity.

"(This is) because the predicted economic benefits would accrue to the present generation but the long-term environmental, heritage and agricultural costs will be borne by the future generations," it ruled.

Australia is the world's biggest exporter of coal which is a significant contributor to its earnings.

Coal has strong support especially around the country's north-eastern fringes where there is little other industry.

Support for coal helped carry Australia's Liberal National Coalition to a surprise election victory in May.

KEPCO had proposed mining up to 6.5 million tonnes of coal a year for export. It has sought permission since at least 2014.

"KEPCO is disappointed in the decision and we are reviewing the statement of reasons for (it)," a Bylong Coal Project spokesman said.

"It's a very significant decision," said barrister Chris McGrath of Higgins Chambers in Brisbane.

"The commission hasn't rejected this mine based on just climate change, it's a whole host of things, including the potential impact to ground water... (however) climate change is an important part of the reasoning, it's not just a trivial throwaway. That's the significance."

The commission last month refused to extend the life of Australian Pacific Coal's mothballed Dartbrook coalmine, partly due to a lack of information on its expected carbon emissions.

In that case, the commission also ruled the extension would not be in the public interest.

Wednesday's ruling is the third this year to signal tighter approvals for coal in New South Wales. In a landmark ruling in February, the state's land and environment court ruled against developers in the country's first legal review of a coalmine project to hear evidence from a climate scientist.

"Today's decision is hugely significant and appropriate just days ahead of the global climate strike and global climate week in New York," said Amanda McKenzie, chief executive of environmental lobby group Climate Council.

"This decision is one that considers our young people and future generations," she said in a statement.