At least 15 mining firms in South Africa have received notices of strikes to be held next week in support of colleagues at Sibanye-Stillwater who downed tools over wages and job cuts, Minerals Council South Africa said on Friday.

The Association of Mineworkers and Construction Union (AMCU) has been on strike at Sibanye's bullion operations since mid-November and plans to extend the strike to its platinum mines as well as all other mines where the AMCU has members.

Firms to be affected include AngloGold Ashanti, Harmony Gold, Anglo American Platinum and Lonmin, whose shares fell on Thursday after it said it had received a strike notice.

Sibanye-Stillwater last week said it could cut nearly 6,000 jobs at its gold mining operations, where AMCU has been on strike since mid-November over a wage dispute.

Job cuts are politically sensitive in South Africa, where the jobless rate is more than 27 percent.

The council, which represents the mining firms, said it was "deeply concerned" about the potential consequences of the strike particularly in the gold and platinum sectors.

"It is unfathomable that AMCU would willingly call for secondary strikes in an industry that is already in jeopardy," Minerals Council Chief Executive Roger Baxter said in a statement.

"Employees and their families, and indeed the country as a whole, stand to lose so much should the secondary strikes occur."

The strikes add to challenges facing President Cyril Ramaphosa, whose efforts to revive an anaemic economy ahead of national elections in May have been complicated by a financial crisis at state power utility Eskom.

South Africa is home to the world's biggest platinum group metals deposits and accounts for just over 90 percent of global production.

The mining firms were considering the notices and vowed to "everything in their power" to prevent a strike, including legal action, the council said in the statement.