South African miners are battling a growing threat kilometres underground in the world’s deepest platinum shafts: gangs stealing copper cables and disrupting operations. 

Enticed by high copper prices, thieves are sneaking in, descending deep underground and setting up camp among vast networks of tunnels to strip metal from power cables. The country’s platinum giants are struggling to contain the syndicates of trespassers known as “zama zamas”, a Zulu name that means “take a chance”.

Illegal mining has long been a problem in SA, though now thefts of equipment are becoming a major worry. The incidents, in some cases daily, can halt work for about a week at a time as cable cuts cripple systems such as locomotives that take ore to the surface...