Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
SOLIDARITY union said on Friday the latest pay offer for members in the paper sector was "unacceptable" and agreement on a rise below inflation was out of the question.
Sappi and Mondi have offered increases of between 6percent and 7,5percent, up from their initial offer of 4-5percent.
The unions are demanding a wage increase of 12percent and a 10percent increase in employees' shift allowance.
"An increase below inflation is simply unacceptable," Solidarity spokesman Jaco Kleyhans said.
"Until a living wage is offered an agreement is out of the question."
South African inflation stood at 8percent in May.
The paper industry has struggled for six years to climb out of a slump, burdened by overcapacity and soft prices