"The current mine was started in 2005 and will expire in couple of years" said Centennial spokeswoman Katie Brassil.

"We are now moving ahead with plans for the next stage as was always envisaged," she said.

The company is well into borehole exploration of another 4170 hectares of its original lease extending as far south as Warnervale.

"The results so far appear to be very similar to the first stage of the Mandalong mine so we have every reason to be hopeful that we will be able to continue the underground operations in exactly the same way," Ms Brassil said.

"When we first started it was a new project but we now have a strong track record of proven accurate predictions which is a big help for property owners in the area and the community's peace of mind," she said.

Ms Brassil said the extension of Mandalong is exactly that.

"There are some who will see it as a new mine but all we will be doing is following the coal seam we are currently mining," she said.

"We will using the same surface infrastructure we have now, the same drift access and the same staff for the extension. The only thing that will be new is the longwall as the current one will be exhausted. It's normal mine progression," she said.

"We have been holding community information days to keep all stakeholders informed and we will continue to do that," she said.