BBC uncovers child sex abuse in South Africa's illegal mines

The most shocking thing for Jonathan, who had endured six gruelling months living and working underground in an abandoned South African gold mine, was the abuse he witnessed being meted out to children.

Some are recruited for cheap labour, but others are brought in specifically for sex, campaigners say.

Jonathan, now in his late 20s, had migrated to South Africa from a nearby country on the promise of making easy money working in one of its dozens of disused mines, closed by multinationals because they were no longer commercially viable.

We are protecting his full identity as he fears reprisals from the vicious criminal gangs that run the illegal mining industry for speaking to the media.

Details of what the young people were going though emerged after the death of dozens of illegal miners near the town of Stilfontein late last year when the mine was blockaded by police.

In a calm and steady voice, Jonathan describes the heat, long hours and limited food and sleeping options which took a toll on his body.

But an enduring memory is what happened to the underage miners in the shaft where he worked.