NSW Minister for Planning Brad Hazzard has joined Rio Tinto subsidiary, Coal & Allied, in appealing the court’s decision to knock back the Warkworth expansion, despite it receiving the department’s director-general approval.

A statement from the Department of Planning states: “The original decision in the Land and Environment court may have implications that are broader than this particular development, in particular for the assessment of other mining projects.”

Rio Tinto has warned of further job losses at its Mt Thorley Warkworth coal mine, despite the Supreme Court’s decision to expedite the company’s appeal against the barring of an expansion of the operation.

The Land and Environment Court last month overturned the development consent received in 2012, based on an appeal initiated by the Bulga-Milbrodale Progress Association.

The matters will now be heard on July 30 to August 1.

However, C&A managing director Darren Yeates said that while the company welcomed the decision to expedite the appeal, pressure on the mine increased each day.

“We'd gone through the full planning process over several years and secured approval from all the necessary state and commonwealth regulators,” he said.

“Suddenly at the end of all of this, for the first time ever, a NSW court has overturned a major project approval to extend an existing open cut mining operation.

“So we now have a new hurdle suddenly added in at the very end of the approvals project - it sends all the wrong signals to any company looking to invest in New South Wales.”

Australian Coal Association chief executive Nikki Williams warned that the decision put future investment in Australia at risk, particularly if governments continued to ignore the impact of high costs, delays and uncertainties in the approval process for mining projects.

The future of Boral’s Medway colliery in Berrima was given a boost last month by Hazzard lodging an appeal against the Land and Environment Court ruling that refused project approval for a $4 million mine expansion to 460,000 tonnes per annum.

Underground contractor Delta SBD has a whole of mine contract with the historic NSW colliery and also lodged an appeal against the Environment Court ruling, which overturned a Planning Assessment Commission approval in June 2012.

“Delta SBD … advises that a second appeal against the above ruling has been lodged by the NSW minister for planning and infrastructure,” the company said.

“Delta SBD will continue working closely with Boral through the appeal process and will provide further information when it is available.”

Boral is continuing operations at the 200,000tpa Medway colliery while the appeals are being heard in the Environment Court.