At least 14 suspected illegal miners were killed and eight injured when a mine dump collapsed in South Africa's North West province on Monday night, police said.

Search and rescue operations were under way for an unknown number of people who may still be trapped at the site near Rustenburg, provincial police commissioner Arthur Peter Adams said.

The collapse occurred as the miners were digging for platinum group metals at a disused dump on a private company's site, Adams said.

The injured miners are from the Southern African country of Lesotho, while the nationality of those killed has yet to be confirmed.

Illegal mining has plagued South Africa for decades, ranging from small-scale theft to operations run by organised criminal networks.

Undocumented miners often enter abandoned commercial mines to extract remaining deposits, sometimes under the control of violent gangs.

Illegal mining costs the government and mining industry hundreds of millions of dollars each year in lost sales, taxes and royalties.