Protesters chanting "Blood on his hands" briefly halted South African Deputy President Cyril Ramaphosa's evidence at an inquiry into the police shooting of 34 striking mine workers in Marikana two years ago.
Retired judge Ian Farlam, who is leading the investigation, halted the inquiry for several minutes on Monday until the crowd, in a public gallery overlooking a conference hall Pretoria, calmed down.
Ramaphosa was a non-executive director at Lonmin when negotiations to halt a violent strike at its Marikana platinum mine ended in police shooting the strikers dead on August 16, 2012.
The killings, the deadliest security action since the end of apartheid in 1994, have become known as the 'Marikana massacre'.
Trade unionist-turned-billionaire Ramaphosa, seen as the likely eventual successor to President Jacob Zuma, is the most
prominent witness to be called by the inquiry that began in October 2012 and was supposed to last four months.
As well as investigating the shootings, the commission has a remit to look into labour relations, pay and
accommodation in South Africa's mines - issues seen as spurring the strike that preceded the killings and that have lingered through months of strikes again this year.
Ramaphosa, who led a historic strike for fairer pay for black miners under apartheid in 1987, has faced accusations of
putting political pressure on the police to use force against striking miners before the shooting.
One protester shouted "Liar!" at Ramaphosa as he answered questions about his time at Lonmin, before more than a dozen people wearing T-shirts denigrating US-style capitalism began chanting: "Blood on his hands."
Ramaphosa told the inquiry his intervention was intended to prevent further loss of life, after at least nine people had
been killed in the days before the police shooting, including two police officers and Lonmin security guards.
"With a grave situation unfolding at the mine, I felt duty bound to help. To prevent further loss of life," Ramaphosa said,
explaining why he made contact with Lonmin leadership and cabinet members.
The inquiry's questioning was focusing on emails sent on August 15, 2012, a day before the police shooting, betweenRamaphosa and Lonmin's chief commercial officer Albert Jamieson.
In one email, Ramaphosa said "concomitant action" was needed to address "dastardly criminal" actions by wildcat strikers, adding that he would contact government ministers.
In an email later that day, he said then-Mining Minister Susan Shabangu would be briefing Zuma and would "get the minister of police, Nathi Mthetwa, to act in a more pointed way".
Ramaphosa told the committee he meant the police should protect lives and arrest miners who had committed crimes but said he did not direct anyone to take specific action.
The former trade unionist left his position at Lonmin in January last year, shortly after becoming deputy president of the ruling African National Congress.
No one has been prosecuted over the Marikana shooting.