Rustenburg (South Africa) (AFP) - Deep underground, where huge conveyer belts haul rocks to the surface, 33-year-old mother of two Bernice Motsieloa represents the quiet revolution transforming the macho culture of South African mining.

Motsieloa is a shift supervisor at Anglo American's Bathopele platinum mine -- one of several thousand female miners employed in a difficult and often dangerous environment traditionally dominated by men.

Despite an apartheid-era ban on women working underground only being lifted in 1996, 15 percent of all employees in the mining sector are now female, exceeding the government's own target of 10 percent.

But reports of sexual harassment are common, and some retired miners say female miners face pressure to offer sexual favours to their male colleagues.

Motsieloa said she has never suffered physical violence since first going down the pits in 2002 doing manual labour in a gold mine, though she vividly recalls the verbal abuse she endured.

"It was hard. We were openly called names by our male colleagues who told us 'this is not your place'," she told AFP.

"At first it was not easy, I wanted to quit. We had to put up with men who were not used to working with women."

A few kilometres from the Bathopele mine, a female worker was raped and killed underground in another Anglo American Platinum mine in 2012. A blood-stained stone was left next to her body.

Three months ago, another female worker was raped in the changing rooms at a different mine also owned by the firm, but escaped with her life.

"I was shocked and did not trust this environment anymore... Working alone, what if this happens?" said Motsieloa, who is always in radio contact with the control room at surface level.

"It really had an effect on me. I was thinking, 'what if someone just shows up?'"

- Tough workplace -

Whatever the challenges, Motsieloa exudes authority as leader of her mainly-male team of 22 workers, and she dismisses any suggestion she might consider a change in profession.

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"For me, mining was not my first choice, but I ended up doing it," she said. "Now I love it. For me, being underground is like being in an office."

It is an unusual place to earn a living -- in a pit as deep as 350 metres (1,150 feet), surrounded by heavy machinery and tunnels marked with danger signs.

Lighting is minimal, with lamps mounted on hard-hats illuminating the path ahead and ghost-like visions of men in white overalls.

Nozuko Ogyle, one of three women on Motsieloa's team, said she felt that women needed to work twice as hard to be taken seriously.

"The job is physically challenging, and as women we must show that we can do it," the conveyor-belt attendant said.

"I do hear about stories of harassment but not here, where I work."

Anglo American Platinum, the mine owner, is South Africa's largest private sector employer and has 3,081 women working in underground operations.

It has introduced a "buddy buddy" system to ensure that women don't work alone when down the mines, as well as setting up a sexual harassment hotline.

Other new safety measures include surveillance cameras and biometric identity turnstiles at entrances to women's changing facilities.

"Women have been able to talk to us and say 'you should do this'... so I think there will be an ongoing process to make women feel safe in our mines," Chris Griffith, CEO of Anglo American Platinum, told AFP.

South Africa has one of the highest rape rates in the world, according to official statistics, though exact global comparisons are difficult.

About 46,250 rapes were reported in 2013/14, and the South African Medical Research Council has estimated only one in nine cases are taken to the police.

- 'Sexual favours' -

Research by Asanda Benya of the University of the Witwatersrand in 2009 found that women were being exploited in mining, a key South African industry that employs about a million people.

The study, entitled "Women in Mining: A challenge to occupational culture in mines", collected witness evidence that shift bosses engaged in sex with female mine workers.

"Men still see women as sexual objects, and as a result transactional sex is on the rise," it said. "Sexual favours are very common underground."

Retired miner Elias Mkhonza acknowledged that sex was an issue in mines, with some men demanding sexual favours in exchange for helping women with strenuous tasks.

"'I do your job, you give me something.' It's like that," he said. "Many do it underground because, once we are out, people go (back) to their partners."

The veteran mineworker, with 22 years of experience in the gold sector, believes that women are not suited for mine work and should "never be allowed underground".

But Motsieloa strongly disagrees.

After getting bored with manual labour, she approached her manager and started training in 2006, first becoming a skilled miner and then a supervisor.

"I have learnt that there is nothing that is out of reach. If men can do it, then women can do it even better," she said, adding a warning to employers.

"Women don't just need to seize the opportunities in order to succeed, they also need support from the bosses."