A work stoppage is underway at Lonmin's Western Platinum mine in Rustenburg, a union official said on Friday.

"We are not calling this a strike. There is a stoppage at one of the shafts," said National Union of Mineworkers's regional chairperson, Elfus Ngoepe. He estimated that 3000 workers were involved in the stoppage.

He added that workers had downed tools in solidarity with their colleagues who were recently dismissed.

The reason for the dismissal stemmed from the workers wanting an apology from management after an underground lift did not arrive on time.

The Lonmin workers are demanding that the dismissed workers be reinstated and that no disciplinary action be taken against other workers over the incident.

The Num's Ngoepe said the company had threatened the union with legal action.

He added that the union did not want the dispute to end in a strike and it was therefore acting responsibly in trying to resolve the situation.

"We are making efforts to normalise the situation," he said.

"We'll do our level best to resolve this."

Meanwhile, Lonmin's spokesperson Alex Shorland-Ball said from London there was no work stoppage at the company's Western Platinum mine.

"Yes, we have dismissed some people but we have a normal turnout at the mine today (Friday)," she said.

Lonmin is a primary producer of Platinum group metals and all its operations are based in South Africa.

The group is a FTSE (London) listed company with a dual listing on the Johannesburg Securities Exchange.

Sapa