The organisation, the Hunter Environmental Lobby (HEL) and supporters from Sydney are also contesting the impact of the mine’s expansion on groundwater systems and on biodiversity.

Their action throws the gauntlet down over the whole issue of the contradictions inherent in NSW’s continued exploitation of coal in the face of concern about the impact of coal-fired electricity generation on greenhouse gas emissions and global warming.

Approval for the expansion was granted last November by former NSW Planning Minister, Tony Kelly, who this week announced he would resign from the Legislative Council to spend more time with his family.

HEL president, Jan Davis, said Xstrata planned to double its production from the mine to 20 million tonnes a year over 10 years.

She said the resulting addition of a further 575 million tonnes of carbon into the atmosphere would speed up climate change.

“Companies the size of Xstrata have the resources to move towards more environmentally safe activities”.

HEL spokesperson, Bev Smiles, said Xstrata’s own studies showed groundwater systems would take up to 200 years to recover.

She said also the company would need to clear areas of the endangered grassy white box woodland for the mine expansion.

“If it was a farmer there is no way in the world they would be given approval to clear.”

In a brief statement Ulan Coal said: “We take our responsibility for the management of the environment and mining operations seriously and have transparently outlined to all relevant authorities our groundwater, ecological and greenhouse gas management strategies throughout each stage of the application process”.

Hearing of the case in the NSW Land and Environment Court began this week.