London - South Africa's government-allied mining union has lost up to 20 000 members since the start of 2012, a year marked by painful strikes and loss of life, the union's leader said on Monday.

The exodus from the once-dominant National Union of Mineworkers began in January, when an upstart rival union promised pay hikes for drill operators at a mine in Rustenburg operated by Impala Platinum.

“In Lonmin and Impala we're looking at about 15 000,” Frans Baleni, general secretary of the NUM, told Reuters in reference to two key mining companies. “In Lonmin the last calculation was about 5 000.”

Despite shrinking numbers, “the NUM remains relevant” in the world's No.1 platinum producing country, Baleni said.

“There is no doubt about it. We are a 30-year-old union.”

In the past, the NUM has contributed stability to South Africa's most heavily unionised industry partly thanks to a cosy relationship with the ruling African National Congress, but both groups have rapidly lost credibility among the country's miners.

Impala says the proportion of its employees affiliated to the NUM has shrunk from 70 percent to 13 percent in seven months.

Thirty-four strikers killed by police at Lonmin's Marikana mine in August were affiliated not with the NUM, but the rival Association of Mineworkers and Construction Union.

Platinum producers lost 350 000 ounces of output during the months of industrial action, but, notwithstanding the upheaval, Baleni said the NUM would oppose any cutbacks in the sector.

“Our job is to preserve the jobs and create job opportunities and we always confront companies which are embarking on an exercise which would lead to dismissals and layoffs of workers,” he said.

Anglo American Platinum is conducting a review of Amplats, its local unit. The review is widely expected to lead to shaft closures and job cuts.

“We are aware that Anglo has been contemplating its presence, especially in the platinum sector,” Baleni said.

“We think that it would be a disaster to shut down Anglo platinum operation with over 30 000 workers involved. We would challenge that.” - Reuters