AAP

Rio Tinto Ltd subsidiary Coal & Allied Industries Ltd has entered into a deal to sell its undeveloped Maules Creek coal project in NSW's Gunnedah Basin to a private Australian mining investment company for about $480 million in cash.

Coal & Allied said in a statement on Wednesday that Brisbane-based Aston Resources Pty Ltd had agreed to buy the asset.

"The Maules Creek coal project did not form part of Coal & Allied's short-term or medium-term development plans," Coal & Allied managing director Bill Champion said.

The company will make a net profit of about $340 million from the transaction.

It said it would consider how best to apply the proceeds of the sale and would provide further information once the deal has been completed, which is expected in early 2010.

"Completion of the transaction remains subject to customary closing conditions, including regulatory approvals," the Rio Tinto subsidiary said.