Johannesburg - Impala Platinum, the second-largest producer of the metal, said it is seeking an explanation for a strike by about 2,000 workers at its Marula mine in South Africa.

No labor union or group of employees has taken responsibility for the walkout that started July 4, Johan Theron, a spokesman for Johannesburg-based Impala, said today by phone.

“We trying to establish who’s in charge and what it is they want.”

Workers could be discontented about a wage deal signed in 2013 that’s valid through June 2015, he said.

The strike follows a five-month stoppage by at least 70,000 workers at other mines owned by Impala and shafts operated by Anglo American Platinum and Lonmin.

The walkout, which paralysed most production sites in the country that is the world’s biggest supplier of mined platinum, ended June 24 when the companies signed a wage agreement with the Association of Mineworkers and Construction Union, or Amcu.

The National Union of Mineworkers is the majority union at Marula, which produced 39,200 ounces of platinum, or 6 percent of Impala’s total mined output during the six months ended December.

Impala also runs the world’s largest platinum mine near Rustenburg, northwest of Johannesburg.

The NUM isn’t aware of the reason for the stoppage and is waiting for the outcome of a meeting between mine management and workers, Phillip Vilakazi, a regional secretary for the union, said by phone.

Employees can be fired under South African law for joining strikes that start before dispute processes have been exhausted. - Bloomberg News