Thousands of co-workers and relatives of 34 miners shot dead by South African police during a violent wage strike will gather Friday to mark the first anniversary of their deaths.

Crowds will amass near the dusty outcrop at Lonmin's Marikana mine where on August 16, 2012 police unleashed a 284-bullet barrage that plunged South Africa into crisis and shocked the world.

Religious leaders will hold prayers, a roll call of the slain miners will be read and there will be a "blow-by-blow account of the massacre," according to organisers.

The event will culminate in a moment of silence shortly after 1400 GMT, around the same time a year ago police opened fire at the foot of a hill.

In the run-up to the killings at least 10 other people -- including two police officers -- died amid a highly charged work stoppage over higher wages at the London-listed mining firm.

With fury over the men's deaths still raw, on the eve of the commemorations the country's national police commissioner called for calm.

"We wish to appeal to everyone who will be in attendance to conduct themselves appropriately," said Riah Phiyega, who as commanding officer gave evidence before a state inquest into the bloodbath.

"Most importantly, we plead with them to not carry dangerous weapons including knives, knobkerries (clubs), firearms or any other dangerous weapons."

The inquest has yet to conclude, mired by delays and bogged down by disputes about the lack of state funding the victims' legal fees.

No one has been held responsible for what many call the worst violence since apartheid ended in 1994.

"We still haven't got the facts of what happened at Marikana, the commission of inquiry hasn't wrapped up its work - we are not close to knowing who is legally responsible for the deaths of 34 miners," said political commentator Eusebius McKaiser.

Amnesty International's Noel Kututwa warned accountability was needed.

"The long-term consequences for the respect and protection of human rights in South Africa will be severe should the South African authorities fail," he said.

But a year on and the events at Marikana remain politically fraught.

The ruling ANC has said it will not participate in the memorial, saying it did not recognise the organisers -- a group linked to a militant mining union.

"The ANC finds it immoral and totally unacceptable that such a traumatic incident could be turning into a political playground by some political parties," the party said in a statement.

Two days before the anniversary President Jacob Zuma issued a statement urging peace, prayers and reflection on the day.

No government representative is listed to address the ceremony, according to the programme seen by AFP.

The event is being organised by a group linked to the Association of Mineworkers and Construction Union (AMCU), which has fought a sometimes bloody battle for power with the ANC-allied National Union of Mineworkers (NUM).

Several targeted assassinations have taken place over the last year, with leaders from both sides dying amid the battle for supremacy.

AMCU's leader Joseph Mathunjwa is expected to give a keynote address at Friday's events.

He had earlier in the week extended an invitation to NUM's leaders "to be part, and join me in Marikana... to preach peace and demonstrate that workers' unity is a strength."

But at the 11th hour, NUM announced that it will stay away because the event has been "hijacked."

The move shredded hopes that the two unions could use the event to move beyond deadly violence between its members.

It is likely that the controversial populist politician Julius Malema, former ANC youth league leader who has recently launched his own party, will be among the speakers giving messages of support.

His party is pushing for the nationalisation of mines, a cornerstone of Africa's largest economy.

"Even as we are remembering victims we are quite frankly messing with their memories by playing politics with the commemoration, politicising the commemoration itself," said McKaiser.

"It means we haven't learnt lessons."