Using a handkerchief to wipe his eyes, he said Association of Mineworkers and Construction Union (Amcu) leaders had gone to a hilltop where protesters had gathered, without a police or a security escort, or any supervision.

"I pleaded with them: 'The writing is on the wall, they are going to kill you'," said Mathunjwa, who is Amcu's president.

Police opened fire on the protesters, many of whom were armed, on Thursday afternoon while trying to disperse them after a week of violent protests that claimed 10 lives.

Mathunjwa said he twice pleaded with them to leave the Wonderkop hilltop, where they had based themselves, but they refused.

"They wanted R12,500 [monthly pay]," he said.

He said he and Lonmin management had tried to discuss a wage increase, but that the mine's management had refused to meet the workers.

He said the striking workers had refused to move before the shooting.

"I told them to leave... I pleaded, I pleaded," he said as tears rolled down his face.

The workers refused. They said they would stay, even if they were killed.

Mathunjwa said President Jacob Zuma should order a probe into the shooting.

"It is with great regret... and shock... that this resulted in a loss of lives," he said.

He said the killings could have been avoided and called on the nation to mourn those who died.

Amcu would assist with funeral arrangements where it could.

The union believed the week-long labour protest should have been treated with sensitivity.

Mathunjwa began the news briefing in Johannesburg by asking that a moment's silence be observed.

Amcu and the National Union of Mineworkers are believed to be in a wrangle over union recognition at the platinum mine.

34 killed, 78 injured

Thirty-four people were killed at a shooting on a hilltop near Lonmin mine at Marikana in Rustenburg, national police commissioner Riah Phiyega said.

"The total death of the protesters currently stands at 34 with more than 78 injured," Phiyega told reporters.

A total of 259 people were arrested and six firearms recovered.

"This is no time for blaming, this is no time for finger-pointing. It is a time for us to mourn...

"The police had to use force to protect themselves from the... group," said Phiyega.

The leaders of the Marikana protesters tried to no avail to get a peaceful solution throughout the week, she said.

Weapons taken off the dead protesters included firearms stolen from the two police officers who were murdered earlier in the week.

Earlier at the briefing, the police showed video footage of how two policemen were killed by a group of protesters.

The video showed police officials confronting the group, asking for weapons.

The men told the police the weapons would be handed over at the mountain, and the police followed them there.

At the hilltop, the incident turned violent and the two police officers were killed.

Journalists were also showed aerial photographs of the naked men doing a ritual with a sangoma.

The group was described as "pretty militant".