South African coal miners began a strike on Sunday after wage talks collapsed last week, disrupting the sector that produces the country's electricity and exports coal to Europe and Asia.
The National Union of Mineworkers (NUM), which organised the strike, said last week that it would begin from 1800 local time (1600 GMT). About 30,000 workers could take part.
"The strike has just started. As expected our workers have downed tools," NUM spokesman Livhuwani Mammburu told Reuters.
Two smaller unions which mostly represent skilled workers and supervisors accepted the coal companies' offers last week.NUM's arch rival, the Association of Mineworkers and Construction Union (AMCU), has not accepted the offer but its membership levels are small.
The Chamber of Mines, which represents Glencore, Anglo American Coal and Exxaro, said last week that the coal producers had raised their offer to increase wages by up to 8.5 percent for the lowest-paid workers, from 8 percent previously.
South Africa's inflation rate is 4.6 percent.