Visitors to Durban's Westville prison were turned away at the gate after a fresh round of violence broke out between three gangs yesterday.
The violence broke out in the medium B section that houses hardened criminals and several inmates suffered stab wounds.
There are three main gangs at Westville prison - the 26s, the 28s, and the Forum.
This is the second violent incident in less than three days.
On Sunday an inmate was killed and another narrowly escaped death when violence broke out.
It is believed that two inmates were stabbed shortly after visiting hours.
The Justice for Prisoners and Detainees Organisation for Human Rights called on Correctional Services Minister Ngconde Balfour to establish a commission of inquiry into the incidents.
KwaZulu-Natal chairperson of the organisation, Derrick Mdluli, said yesterday's violence resulted in the cancellation of all visits.
"I went to the prison to meet some inmates, but I was turned away.
"Officials said it was not safe for visitors to enter the premises following the violence.
"But information about the injured inmates is still sketchy. The Westville situation needs more attention from the minister," he said.
Correctional Services regional manager Mnikelo Nxele said visitors were barred from the prison for their own safety.
"A fight broke out between inmates who were armed with padlocks. We could not allow visitors in as we were trying to bring the situation under control," he said.
Nxele said the department was considering implementing a system where visitors would make appointments before visiting.
"We are trying to get to the bottom of the incidents and how the weapons were smuggled in."