An initiation school in Mpumalanga was used as a sex den where 21 girls aged between nine and 17 were repeatedly raped and physically abused, the Nelspruit circuit of the High Court in Pretoria heard on Wednesday.

One of the 21 girls testified against Johan Jabulani Mlombo, 48 and his wife, Sister Mapalase Khoza, 41, both from Masoyi near Hazyview, a Sapa correspondent reported.

The couple have been charged with assaulting and raping the girls at their initiation school in Mahushu, on August 29, 2012.

Both accused have pleaded not guilty to 27 charges of rape, three of sexual assault, and 19 of assault with intent to cause grievous bodily harm. They have been granted R1000 bail each.

"Accused one, the following day after the night he raped me, called us one by one after we returned from bathing at a river," said a 17-year-old girl who testified via a video link.

"He said I was nice and he would call me again."

The girl, who said she was partially blind, told the court Khoza called her away from the corrugated iron shelter where the initiates slept.

"I was the sixth victim to be called that night. She told me I had to see the big initiation and after we entered the main house, accused two asked me to enter inside a dark room.

"When I refused, she pushed me inside, closed the door, locking me inside with a male person. She did not enter but remained outside," she said.

The girl testified the man inside gave her a cup of water to drink. He then told her never to tell anyone what was going to happen next.

"Although it was dark inside, I could feel he was naked on top and covered with a cloth at the bottom, because I touched and felt him. Using his hand, he removed my panties, climbed on top of me and raped me," she said.

The girl testified she had been at the initiation school since June 2012.

"My parents wanted to remove me from this initiation school but accused two (Khoza) refused. We were forced to fetch firewood guarded by two people."

She testified that Khoza used to hit her on her back with a stick.

"The stick was flexible and not an ordinary stick from a tree. I was assaulted many times because I was stubborn. One day I was assaulted after I refused to carry a big container of water. They ordered me to carry the bigger one as I was the eldest," she said.

The girl said Khoza used a hot iron to make round marks on her and all the girls' cheeks.

"I never agreed with her to make the mark. It took two weeks to heal and left a scar that will remain for the rest of my life," she said.

Khoza's lawyer said she would testify that she never assaulted the victim, but had performed initiation rituals.

The trial continues.