The mineral-rich country counts thousands of illegal miners, whose activities frustrate mining companies and are seen as a source of criminality by local residents.

Ramaphosa has "authorised the employment of 3,300 members of the South African National Defence Force (SANDF)" to "conduct an intensified anti-criminality operation against illegal mining across all provinces," the president's spokesman Vincent Magwenya said, adding that they would work alongside the police force.

The operation will run until April next year, costing state coffers almost 500 million rand ($27 million), he added.

Commonly known as "zama zamas" ("those who try" in the Zulu language), informal miners are mainly foreigners who come to South Africa to try to earn money from clandestine pits, living and working in arduous conditions.

The Johannesburg region is dotted with slag heaps, shafts and deep trenches left by generations of miners, whose arrival in a gold rush in the 1880s led to the birth of the city.

Access to the old mines is often controlled by rival gangs that sometimes battle for authority causing outbreaks of violence.

Illegal operations also affect active mines, something that mining companies have long complained costs them money and is a threat to their staff.

In July, five people were shot dead near an abandoned shaft west of Johannesburg while last year illegal miners in a nearby area were blamed for the shocking mass rape of eight women.

Amid high unemployment, illegal immigration and rampant crime are seen as key political issues ahead of general elections next year.