* Experts say measure not used since apartheid times
* Say charges inflame already tense situation
* Talks resume to get workers back next week
* Mines minister says unrest could hit investment
JOHANNESBURG, Aug 30 (Reuters) - South African prosecutors on Thursday charged 270 striking miners with murder of 34 co-workers seen being shot dead in a hail of police bullets captured in videos broadcast around the world.
Prosecution have filed papers invoking a measure called "common purpose" seldom used since the dying days of apartheid, arguing the miners were complicit in the killings since they were arrested at the scene with weapons.
Legal experts said the move will likely collapse when a court hearing bail applications for the 270 near the mine resumes sessions next week and lambasted prosecutors for inflaming a tense situation by seeking a mass indictment that will eventually be rejected.
"This is bizarre and shocking and represents a flagrant abuse of the criminal justice system in an effort to protect the police and/or politicians," Pierre de Vos, a law expert at the University of Cape Town, wrote in a blog entry.
"The apartheid state often used this provision to secure a criminal conviction against one or more of the leaders of a protest march, or against leaders of struggle organisations like the ANC."
President Jacob Zuma and his ruling African National Congress have faced increasing pressure over the killings, which are the deadliest security incident since apartheid ended in 1994, with many saying the government may be more concerned about protecting its own than miners in shafts.
The government has launched a probe into the killings, including the deaths of 10 people ahead of the shooting at Lonmin's Marikana mine, northwest of Johannesburg.
It is withholding any police punishment until the investigation is over in around January.
The Independent Police Investigative Directorate, a government watchdog, said it had received nearly 200 complaints from the arrested miners of being assaulted and abused while in custody.
Fewer than 7 percent of Lonmin's 28,000-strong South African workforce reported for duty on Thursday as the platinum producer held talks with warring unions, attempting to cool tensions and bring people back to work.
The world's third-largest platinum producer has been forced to shut its mining operations for almost three weeks because of a violent turf war between the established National Union of Mineworkers (NUM) and militant Association of Mineworkers and Construction Union (AMCU), which led to the deaths of 44 people this month.
We have a 6.6 percent average attendance across all shafts this morning," Lonmin said in a statement.
The talks to end the impasse in the platinum mining city of Rustenburg, northwest of Johannesburg, resumed on Thursday after dragging into the night on Wednesday.
Gideon du Plessis, deputy secretary general of trade union Solidarity, said discussions are to secure "a return to work agreement - with the aim of getting workers back to work on Monday after most funerals have been concluded".
He said the grievances raised by the striking workers would then be dealt with and finally, a peace accord would be reached.
Solidarity represents skilled workers, and its members have not been on strike, but all unions are taking part in the talks.
The 3,000 strikers who have brought things to a standstill are mostly rock driller operators, who demand a monthly wage of 12,500 rand ($1,500), which would amount to a hike of over 25 percent over what the company says it currently pays, excluding bonuses.
In Australia, South Africa's mines minister, Susan Shabangu, said on the sidelines of a conference that the violence was undermining investor confidence in Africa's largest economy, which sits on 80 percent of known platinum reserves.
"It is a cause for concern. The tragedy does impact on any potential investments. Any investor would like to invest in a stable environment; we've got to recognise that," she said.
Lonmin accounts for 12 percent of the global output of platinum, used in car catalytic converters and jewellery.
Lonmin has said it may issue new shares to shore up a balance sheet hit by lost output and revenue, as well as the prospect of further losses as the entire platinum sector struggles with soaring power and labour costs and poor demand.