Unionised workers at Stillwater Mining Co's operations in Columbus, Montana will vote today on a new labour agreement aimed at ending strike action at the plant.

Nearly 850 workers have refused to work since last Monday when a tentative agreement reached between leaders of the Paper, Allied Industrial, Chemical and Energy Workers International (PACE) union and Stillwater management was rejected by 70 per cent of union members.

However, Stillwater president and CEO Frank McAllister told Mineweb that a new agreement had been reached that addressed some of the workers' grievances.

If the new agreement is ratified the first employees will return to work on Wednesday morning.

Stillwater Mining, operates the only platinum and palladium mine in the United States, employing around 1,500 people.

Palladium accounts for about three-quarters of the pgm extracted, with the remainder largely platinum.