* Deputy president facing questions over "Marikana massacre"
* Protesters chant: "Blood on his hands"
* Ramaphosa is favorite to succeed President Zuma
(Updates after protest, details, context)
JOHANNESBURG, Aug 11 (Reuters) - Protesters chanting "Blood on his hands" briefly halted South African Deputy President Cyril Ramaphosa's evidence on Monday at an inquiry into the police shooting of 34 striking mine workers two years ago.
Ramaphosa was a non-executive director at Lonmin when negotiations to halt a violent wildcat strike at its Marikana platinum mine ended in police shooting the strikers dead on Aug. 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 investigation that began in October 2012 and was supposed to last four months.
As well as investigating the shootings, the commission of inquiry has a remit to look into labor 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 U.S.-style capitalism began chanting: "Blood on his hands."
Retired judge Ian Farlam, who is leading the investigation, halted the inquiry for several minutes until the crowd, in a public gallery overlooking the conference hall, calmed down.
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.
He left his position at Lonmin in January last year, shortly after becoming deputy president of the African National Congress. No one has been prosecuted over the Marikana shooting.
The inquiry's questioning was focusing on emails sent on Aug. 15, 2012, a day before the police shooting, between Ramaphosa 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.
Ramaphosa, once called "South Africa's Lech Walesa" after the Polish labor leader and democracy activist, now finds himself pilloried as a cold-hearted capitalist.
As he took his oath, someone in the chamber shouted: "He doesn't believe in God." Another union member jeered: "He's a sell out."
Ramaphosa was shown old footage at the inquiry of him during his days as the thickly bearded leader of the country's largest mining union, calling passionately for companies to address the inequalities and hardships faced by workers.
Under sometimes awkward questioning, Ramaphosa said he stood by his comments made as a trade unionist, before a member of the inquiry questioned the success of Lonmin to tackle socio-economic problems during his time at the firm.
Ramaphosa conceded that Lonmin only building three houses for workers out of a promised 5,500 between 2006-2011 was "under-performance".
(Editing by Alison Williams)