Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
A looming strike on Wednesday could disrupt construction on Durban's 2010 Moses Mabhida Stadium.
The workers are demanding construction company Group 5 respond to a list of grievances including issues of safety on site.
Spokesman for the National Union of Mineworkers, Bonginkosi Mncwabe, said the workers would "definitely" go on strike should their employer fail to reconsider the workers' demands.
Two months ago, construction was suspended for three weeks after the Department of Labourpaid an unannounced visit to the site.
Officials declared the site unsafe, putting the lives of the workers at risk.
Notices were issued, but revoked the next day.
Mncwabe said regardless of a number of notices that were issued to the employer about issues of safety, nothing has been done by the employer to provide safety.
The workers are also demanding between R1000 and R1500 on top of their salaries as project bonuses each month, an appointment of a full- time safety representative to monitor safety on site.
"What we are asking the employer is so little compared to the millions involved in the building of the stadium.
"The only person who is benefiting is the employer. What about the people that are building this stadium? he asked.
A 70 000 capacity stadium was expected to be finished in October, but this is likely to be delayed should the employer fail to stop the strike.
Mncwabe said construction workers in KwaZulu-Natal have shown their support to join the strike.
He said after negotiations that began in March, we have failed to come to an agreement with the employer after negotiations that began in March. "This has left us with no other choice but to take action that would make us heard," he said.
Mncwabe said they further wanted workers to be given reasonable working hours instead of being exploited by the employer who make them work up to 15 hours.
"The hours that they work are not in line with the law of this country. What the employer is doing, is pure exploitation of workers' rights," he said.
Spokesman for Group Five's provincial project, Craig Jessop, was not available for comment.