Anglo American said on Tuesday it was ramping up output at its South African coal mine to meet its production targets after a 13-day wildcat strike by workers halted operations.
Workers at Anglo's Kleinkopje mine, which produced 3.9 million tonnes of thermal coal in 2014, returned to work last week on Monday after the nearly two-week strike and the firm said it had set measures to recover lost output.
"Our targets are based on the hours worked, if those hours are reduced then inevitably production targets will be impacted," Anglo's spokesman Moeketsi Mofokeng said.
Some workers volunteered to work on Monday, a public holiday, to minimise the strike's impact on production, he said.
Anglo had said the strike started on April 7 and was regarded by the company as a wildcat action because the workers had not gone through the proper channels before calling the stoppage at the mine east of Johannesburg.
[DATA AGL:Anglo] subsequently obtained a court order barring the strike and requiring the workers to resume duty.
Stanley Lebelo, the National Union of Mineworkers (NUM) regional secretary, told Reuters the union's lawyers were preparing a response to the court order.
The NUM had said 400 of its members were on strike demanding that suspensions against five of its leaders at the mine be lifted, as well as the removal of the mine's general manager, whom it said had made changes without consulting the union.
About 1,200 workers are employed at the coal mine and it was not immediately clear how many of them belong to the NUM.
The strike comes just weeks before wage negotiation kick off in the gold and coal sector.