A National Union of Mineworkers (NUM) branch leader was shot dead at his home in Marikana on Friday night, the union said.

Spokesman Lesiba Seshoka called the attack an "assassination". It could not immediately be confirmed with the police.

"This comes after the death of the NUM branch chairperson last weekend and the attack on another branch leader, who escaped whilst his wife was killed," said Seshoka.

He said the man killed was the NUM branch secretary at Western Platinum.

Five NUM members -- two of them shop-stewards -- were killed in violence associated with a strike at Lonmin's platinum mine in Marikana between August 10 and August 16, said Seshoka.

Of the 34 people shot dead by police trying to disperse a group of protesters on August 16, 14 were NUM members, he said.

On September 11, a third NUM shop steward was found dead near the scene of this shooting. Dumisani Mthinti had been hacked to death.

Striking workers at Marikana -- and other mines -- have voiced unhappiness with their NUM representatives.

During an inspection in loco by the Farlam commission of inquiry into the Marikana shooting, a worker claimed NUM members confronted and shot workers -- killing two of them -- who were marching to the union's office on August 11.

Three University of Pretoria sociology department studies on the level of satisfaction among union members, reportedly found that the NUM was dysfunctional in the Rustenburg area.

However NUM general secretary Frans Baleni denied that the union was under-servicing its members. There have been calls for his resignation.

The strike at Marikana was initially thought to be linked to a struggle for recognition between the NUM and the newly-established Association of Mineworkers and Construction Union (Amcu).

When the violence broke out, each accused the other of inciting the violence.

Amcu claimed the NUM resorted to violence to throw people into disarray whenever it lost members.

It said there was no union rivalry, but that the NUM had "internal issues" which had nothing to do with Amcu.

The NUM claimed a hit list had been compiled containing the names of its members at Lonmin.

Workers sang anti-NUM songs at Marikana, and those at other mines, burnt their NUM T-shirts.

In the end, the workers at Marikana negotiated their own increase with the company -- a 22 percent pay rise and a once-off bonus of R2000 each to return to work -- a settlement which was considered to have set a bad precedent because it was reached outside the bargaining process.