Bloemfontein - Another prison guard was stabbed at the Mangaung prison in Bloemfontein on Thursday, G4S Security said.
There had been stabbings at the prison every day this week, said G4S Africa head Andy Baker, but he could not say how many.
“We have affidavits from inmates that allege that payments are made to carry out attacks,” he said.
Baker said he could not comment about the motives for the attacks on prison staff.
On Wednesday, four inmates held a G4S official hostage for 13-hours at the prison.
She was released when the prisoners were overpowered by a special police task force.
Baker said on Thursday that there were links between the hostage drama and the recent dismissal of 331 G4S employees.
Their contracts were terminated at the end of September after they went on strike at the privately-run prison.
They were members of the Police and Prisons Civil Rights Union.
At the time, G4S Africa spokeswoman Kirsten van der Nest said the company had been in salary negotiation with the employees since November 2012, but that the talks deadlocked in March 2013.
Popcru referred the dispute to the Commission for Conciliation Mediation and Arbitration, which found that G4S's proposals were fair and reasonable.
G4S said no inmates had been disadvantaged as a result of the illegal industrial action and were receiving their meals, medication and exercises.
On Thursday, G4S said any appeals by the dismissed members would be dealt with properly and fairly, and that Popcru was welcome to talk to the company about saving their jobs.
Sapa