Many of the bore sites, which would be about 25m wide, are on private land and one appears to be right on the edge of Nicole Kidman and Keith Urban's $6.5 million Sutton Forest property, Bunya Hill.

State Government approval of the exploration activity on a coal lease around Sutton Forest was made public last Friday - just hours before Planning Minister Brad Hazzard announced a moratorium on new coal and coal seam gas projects.

Mr Hazzard had to admit he did not know about Cockatoo's exploration approval.

Yesterday, Liberal Government minister and local member Pru Goward said she would try to stop the exploration proceeding.

She said drilling would not damage the environment and the underground water body as significantly as a full-scale mine, but she opposed any activity that could damage the aquifer.

"I'm sorry they've started exploring - I think that's a pity," she said.

"We'll see if we can stop even that work happening."

Also yesterday, Cockatoo Coal posted a new message on its website saying it had permission to drill 120 bores over more than 100sq km between Belanglo, Exeter and Moss Vale. Its previous message mentioned only 30.

Hume Coal Project Manager Mike Cunnion said holes would be drilled in cleared areas where possible, and rehabilitated on completion. "Several weeks ago we commenced the process of seeking to gain access to landholders' properties through direct consultation and we will continue that process," he said.

"We will not comment on negotiations with specific individuals out of respect for their privacy."

Landowners can negotiate access for drilling but may not be able to stop the miner completely if the matter is taken to court.

Southern Highlands Coal Action Group co-ordinator Tim Frost has been advising landowners to lock the miner out and said he was not aware of any agreeing to access so far. Hume Coal is a new company formed for the project and owned by Korean steel maker POSCO.

Cockatoo Coal, which has a 30 per cent stake in Hume, is the operator.

The application to conduct the exploration work was approved on May 6 by the NSW Department of Trade Investment, Regional Infrastructure and Services. Three days later, Cockatoo announced it had secured a $50 million bank guarantee from Macquarie Bank to finance its operations.

Belanglo was the site backpacker murderer Ivan Milat used to dump the bodies of seven of his victims, and also the scene of an alleged axe murder this year.