Johannesburg - Unprotected strikes have halted production at three of mining company Exxaro's coal mines, the company said on Friday.
"Issues relating to the strikes at Matla and Arnot are not related to those at Grootegeluk," spokesperson Hilton Atkinson said in a statement.
"The strikes have led to production being stopped and the group is engaging with unions and managing the situation to bring operations to normality as soon as possible."
On Thursday, Exxaro announced unprotected strikes at two of its Mpumalanga mines, Matla and Arnot.
"The strikes at Matla and Arnot in Mpumalanga started on March 5 and are related to non-payment of performance bonuses due to the operations having not achieved their performance targets," Atkinson said.
He said employees were regularly informed of performance levels and bonus payments.
The Matla mine has 18 stock days of supply available and the Matla power station has two stock days of supply on hand. At Arnot there was no risk to supply of coal.
The strike at Grootegeluk in Limpopo started on Friday and involved a range of grievances, Atkinson said.
"The mine has 14 stock days of supply for the Matimba power station and the power station has 33 days of supply stockpiled."
He said the mine also had reasonable supplies of coal for its other domestic and export customers.
"The mines have implemented contingency plans to continue supplying coal to maintain the functionality of their respective power stations."
Atkinson said Exxaro would continue to work closely with power utility Eskom to ensure coal supplies.
Follow Fin24 on Twitter, Facebook, Google+ and Pinterest.