JOHANNESBURG (Reuters) - Workers at the Rustenburg operations of South Africa's Anglo American Platinum refused to go underground for overnight shifts to protest company plans to close mines, a labor leader said on Wednesday.

"They didn't go underground," Evans Ramogka, a labor leader and activist at an Amplats mine in Rustenburg, about 120 km (70 miles) northwest of Johannesburg, told Reuters.

A company spokeswoman said she could not immediately comment because she was waiting for an operational update from managers at the mines.

Local media reported workers would be meeting later to plot wider strike action after Amplats, a unit of global mining group Anglo American, unveiled plans on Tuesday to mothball two South African mines, sell another and cut 14,000 jobs.

Amplats, the world's No. 1 platinum producer, said the initiatives are needed to restore profits. But the company also risks provoking a repeat of last year's violent wildcat strikes that left over 50 people dead.

Amplats said on Monday it would likely fall to a full-year loss because of last year's costly strikes.

(Reporting by Ed Stoddard; editing by David Dolan)