JOHANNESBURG (Reuters) - South Africa's Association of Mineworkers and Construction Union (AMCU) is planning to strike at Sibanye-Stillwater's (J:SGLJ) local platinum operations, it said on Monday, expanding an earlier stoppage affecting its gold facilities.
Since the union downed tools at Sibanye 's gold operations in mid-November, four employees have been killed during strike-related violence and the firm has said it expected to miss its 2018 bullion output forecast.
AMCU said on Monday that the new strike would begin on Jan. 22 and involve around 12,500 of its members.
Sibanye said it was unable to estimate what impact the expansion of the strike would have on operations at its South African platinum mines. AMCU is the majority union at all of Sibanye's local platinum mines.
"There is a strong chance that there will be an operational impact at Rustenburg," Sibanye-Stillwater spokesman James Wellsted said, referring to one of Sibanye's major mines.
AMCU embarked on the strike at Sibanye's gold operations after wage talks with the company broke down, despite the firm reaching a three-year wage agreement with the National Union of Mineworkers (NUM), Solidarity and UASA.
Sibanye says those three unions make up a majority of employees at its gold operations, allowing it to extend the agreement to other minority unions.
Gold producers in Africa's most industrialised economy have argued that above-inflation wage hikes have added to the cost burden of the bullion industry, which has been hit by depressed prices and labour unrest.
Shares in Sibanye-Stillwater were down 0.37 percent to 10.65 rand by 1342 GMT.