Police said on Wednesday they fired rubber bullets, tear gas and stun grenades to break up a march by thousands of strikers at Amplats mines near Rustenburg belonging to Anglo American Platinum, the world's largest platinum producer.
Amplats strike leader Evans Ramokga told AP that a miner was run over by a police armoured car and dragged several metres before it stopped. He said the man died overnight in the hospital.
Police spokesperson Dennis Adriao said he was unaware of the incident but added the armoured cars weigh several tons.
Woman out shopping when struck by bullet
Cosatu condemned the brutality of police who have been harshly criticised for the August 16 shootings of 112 striking miners that left 34 dead at Lonmin platinum mine.
The trade union federation said ANC councillor Paulina Masuhlo was shopping on Saturday near the Never Die Tavern in Wonderkop where Lonmin miners.
Police began firing from a speeding armoured car and hit several women.
Masuhlo was hit in the abdomen and leg and rushed to the hospital, where she died on Wednesday, Cosatu said.
Police spokesperson Dennis Adriao said he was investigating the report of a death. He said police had reported to the Independent Police Investigative Directorate that several people were hit by rubber bullets in a raid to disarm strikers on Saturday, the day after the government ordered a crackdown.
The directorate already has opened 34 murder and 78 attempted murder charges against police.
But no action has been taken against any of the officers involved. The government has said it is awaiting the outcome of a judicial commission of inquiry that is supposed to report to the president in January.
Cosatu called for "the immediate identification and suspension of the police officers involved in [Masuhlo's] murder".
"We are also extremely unhappy that, to date, none of the police officers involved in the massacre on 16 August 2012 has been identified or suspended - this is totally unacceptable and unlawful," Cosatu said.
The deaths at the two mines, both northwest of Johannesburg, bring the toll to 47 dead in violent strikes rooted in union rivalry.
Lonmin on Tuesday resolved its five-week strike by agreeing to pay raises of up to 22%.
Union leaders warned that sets a precedent for other miners to join demands for better wages.
The strike already has spread to several gold, platinum and chrome mines, damaging investor confidence in the country that produces 75% of world platinum and is the No 4 chrome producer and in the top 10 of gold producers.