National Union of Mineworkers general secretary Chris Kitchen urged the South African government today to "reconsider" the arrests of striking platinum miners who have been charged with the murder of 34 of their colleagues shot by police.
In the worst episode of state-related bloodshed since the end of apartheid police shot dead 34 miners.
But the decision by the National Prosecuting Authority (NPA) to charge the 270 workers with the murder of their comrades at the Marikana mine is controversial as the prosecution is relying on the apartheid-era "common purpose" doctrine.
The doctrine holds rioters vulnerable to prosecution for acts committed by police in response to a riot.
Mr Kitchen said: "We are outraged at the way our colleagues have been treated. How can you be charged with murder when running for your life? It's deplorable."
He added that the South African government should now reconsider the arrests.
South African Justice Minister Jeff Radebe has also demanded an explanation.
Mr Radebe said that the decision had "induced a sense of shock, panic and confusion" among South Africans.
In a statement, Mr Radebe said that under the constitution, the justice minister "must exercise final responsibility over the prosecuting authority."
He said he had asked the head of the NPA "to furnish me with a report explaining the rationale behind such a decision."
NPA spokesman Frank Lesenyego told the BBC the 270 workers would all face murder charges - including those who were unarmed or were at the back of the crowd.
"This is under common law, where people are charged with common purpose in a situation where there are suspects with guns or any weapons and they confront or attack the police and a shooting takes place and there are fatalities," he said.
But South African lawyer Jay Surju told the BBC that the "common purpose" doctrine was used by the former white minority regime against activists fighting for racial equality in South Africa.
"This is a very outdated and infamous doctrine," he said.
"It was discredited during the time of apartheid."
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