The group seeks to have the approval overturned on the basis that it should have been assessed by the independent Planning Assessment Commission.

But it was approved by the Department of Planning under the government’s controversial 3A planning laws.

‘‘There was no independent assessment of the impacts of the mine expansion as is usually done when increases in impacts and environmental effects are so massive,’’ lobby spokeswoman Jan Davis said.

Environmental Defenders Office solicitor Natasha Hamond-Deakin said the case was only the second in NSW.

‘‘There is going to be a very obvious environmental impact on ground and surface water, biodiversity, Aboriginal heritage and greenhouse gas emissions,’’ she said.

She said the group was concerned the department lacked the capacity to assess the large number of coalmining expansion applications in NSW.

‘‘We believe the environment is being taken for granted; we have said enough is enough,’’ she said.

Xstrata Coal spokesman James Rickards said the approval was granted to allow consolidation of the mine’s existing approvals.

‘‘It is important to remember the majority of activities to be conducted under the consolidated Ulan project had been approved prior to the 3A application,’’ he said.

The case is due to be mentioned in the Land and Environment Court on March 4.