JOHANNESBURG, South Africa - The death toll from the ongoing violence at a platinum mine in the North West Province has risen to at least nine, authorities said on Monday.

Protests, which broke out on Friday, turned more violent on Monday, claiming the deaths of two police officers, one of them hacked to death, and three miners, provincial spokesperson Brigadier Lindela Mashigo said.

Miners belonging to difference unions attacked each other in protests over low pay at the Marikana mine. In previous attacks, four people were killed, including two security guards whose car was set ablaze by angry miners, police said.

The unions, the Association of Mineworkers and Construction Union (AMCU) and the National Union of Mineworkers (NUM), blamed each other for the violence.

The violence broke out when members of AMCU shifted sides to the NUM, prompting angry reaction from the AMCU, sources said.

The Congress of South African Trade Unions (COSATU), the parent group of NUM, said miners have the right to choose their union.

"COSATU wants to remind AMCU that the Constitution of our country allows workers a freedom of association," COSATU provincial secretary Solly Phetoe said.

"That right has been extended in the Labour Relations Act which gives workers the rights and powers to form their unions, and not to be forced to join some fly-by night unions."

Police said a case of murder, arson, and malicious damage to property has been opened.