A 17-year-old Soweto girl who was gang-raped by seven boys on film is still missing, prompting fears for her well-being.

She went missing on 25 March after the horrific ordeal, which was recorded on a mobile phone and posted on the internet.

The victim can be heard crying and repeatedly calling for help and asking her attackers, aged between 14 and 20, to stop.

The video shows graphic scenes of the girl being sexual assaulted while the men can be heard encouraging each other and joking about their "performance".

At one point they even discuss whether the victim is actively crying or not.

She was reportedly left in the company of an elderly taxi driver in Dobsonville, Soweto, but has not been found and police were stepping up the hunt.

Seven boys were arrested in the area, based on identification from the video.

"Somebody gave the information and it was followed and the boys were identified through that video" officer Kay Makhubele told the South African Eyewitness website.

Makhubele added police were still trying to find the exact location of the assault. They believe the girl was kidnapped and used as a sex slave.

"She's just a normal girl who was captured by the boys and kept there for sexual activities," Makhubela added.

The men will appear in the Roodepoort magistrates' court.

South African Teenage Girl Raped by Gang on Film Found Alive