NUM Kimberley regional secretary Cornelius Manhe said in a statement Wednesday the union had engaged with KEM JV in "fruitless meetings under the watchful eyes" of the Commission for Conciliation, Mediation and Arbitration (CCMA) on the retrenchment issues.

He said the CCMA commissioner had instructed the company and the labour unions to meet separately without his involvement to narrow the issues down.

"What puzzles us is that the company is negotiating in bad faith. They failed to convince the NUM that the retrenchment is legitimate. They failed to provide us with the relevant information that will assist the process," Manhe said.

He said the NUM planned to "fight with everything that is in our power to defend our members from this intransigent company".

There was no announcement from KEM JV on the retrenchments.

The JV is 58.1% owned by Petra Diamonds (LSE:PDL), although the company announced in early July it had decided  to sell its stake, as well as its black economic empowerment partners' interest — together 75.9% — to its JV partner Ekapa Mining for R300 million (US$20.9 million) in cash.

There has been no update on the progress of the sale, but the transaction was subject to certain approvals and was expected to be completed before the end of the September quarter.

The JV includes the Kimberley underground mine, extensive tailings retreatment programmes and the Central treatment plant in South Africa's Northern Cape province.