The mine, which remains on care and maintenance, continues to be delayed as further environmental issues are examined.

"Sealing of old sections of the mine was planned for the first quarter of 2020," the company said.

"Activity will be progressed in the next quarter.

"Work continues on the surface to address redundant equipment and maintain site facilities."

Around the clock security is in place at the eastern mine pit head facility.

Wollongong Coal said work continued in the June quarter to prepare an application to extend the approval period for the New Mine Entries from December 2020 for a five-year period.

"This provides the opportunity to resume mining operations in 2021," it said.