The Oaky North mine is largely being operated by non-union staff and contractors during the lockout, which started in June, with no impact on production, said Glencore spokesman Francis De Rosa.

Glencore and the Construction, Forestry, Mining and Energy Union (CFMEU) have made little headway in hammering out a so-called enterprise work agreement for the mine since the last one expired in mid-2015, despite sitting down at the negotiating table 23 times, according to the spokesman.

The latest attempt, under mediation from the Australian government's Fair Work Commission, failed to bring a resolution closer, with the CFMEU vowing in a statement to "fight Glencore every step of the way".

Stephen Smyth, a CFMEU district president, said the latest move banning union workers from the mine would take the lockout to 132 days.

Coal from the mine is used in steelmaking and is shipped to buyers in Asia, North Africa Europe and South America.

The dispute is focused on wages, benefits, working conditions and hiring practices.

Glencore's proposals include lifting wage rates, which average A$180,000 (104,660.08 pounds) per year including retirement funds by 8.24 percent over the term of a new agreement, according to the company spokesman.

In a statement issued late on Tuesday, Smyth said Glencore ordered the lockout despite the union making some concessions on issues regarding workplace representation and the resolution of workplace disputes.

(Reporting by James Regan; Editing by Joseph Radford)