Rio Tinto and the New South Wales (NSW) Government have allegedly colluded to hasten environmental approval for the Warkworth coal mine expansion in the Hunter Valley, New South Wales, Australia.

Activist group Lock the Gate has sought emails that highlight the co-ordination between Rio Tinto and the government over the approval.

The Office of Environment is said to have requested more information from the mining company regarding the offset package to clear more than 600ha of forest area, which includes 72ha of Warkworth Sands woodlands near Singleton as of 28 October 2014, according to Sydney Morning Herald. The information was provided and certification granted within four working days.

A spokesman from the Department of Planning and Environment said that the emails show its: "Rigorous, transparent process for assessing mining proposals in action, shining a light on the independent nature of the way the department makes decisions."

"The approach of the government appears to be to allow the mine to go ahead at any cost." 

Lock the Gate NSW coordinator Georgina Woods told The Sydney Morning Herald that the release of all email correspondence has been opposed by the government and Rio Tinto, limiting the public’s knowledge of the full extent of cooperation between them.

Woods said: "The approach of the government appears to be to allow the mine to go ahead at any cost.

"The law is no longer capable of preventing extinctions of species and communities."

Previously, the Land and Environment Court rejected claims made by the Planning Assessment Commission regarding the expansion of the mine and said that the resulting economic gains outweighed the environmental impact.

In April 2014, the Court of Appeal of the Supreme Court rejected the company’s bid to overturn the first verdict.

Rio Tinto also faced opposition from residents of the nearby town of Bulga, who said the expansion would encroach on their properties.

A decision is yet to be made by the Planning Assessment Commission on whether to approve a modified version of the company’s mine extension.