More than 500 members of the National Union of Mineworkers have gone on a protected strike at Impala Platinum Holdings Ltd.'s platinum refinery in South Africa after both parties failed to reach a wage deal following five rounds of negotiations.

The talks began in July to forge a new wage deal after the previous three-year agreement expired.

About 85% of the workforce reported for duty and operations are running normally at the refinery, which employs about 900 people, Bloomberg News reported Sept. 27, citing Implats spokesman Johan Theron.

The union demanded a 9.5% increase in pay, while the platinum miner offered a 7.5% raise, NUM Deputy Branch Secretary Mpho Mere told Bloomberg.

"We declared a dispute because we're still far, far apart."

On the other hand, the company is also short on meeting the union's demands for higher housing, shift and standby allowances, and wants workers to use in-house medical insurance plans.

Implats will continue to work to close the gap in talks, Theron noted.

Earlier in the month, platinum miners and the Association of Mineworkers and Construction Union also declared a deadlock during wage talks.