The December 2013 deadline for the Medupi power station to start delivering power will not change, Public Enterprises Minister Malusi Gigaba said on Friday.

"For now, having received the detailed technical plans from the primary contractors in regards to what they must do to meet the December deadline -- which I am adamant will not be changed without strict penalties being imposed on the contractors should they fail to meet their obligations --I am unprepared to accept any review for the delivery schedule," Gigaba said.

He said Eskom simply had to do more and better to manage the contractors and the project itself.

Gigaba was speaking at a business breakfast hosted by The New Age in Midrand, Johannesburg.

On Monday, workers returned to work after the National Union of Metalworkers (Numsa) and contractors reached a resolution on the Project Labour Agreement (PLA), ending a strike which had lasted almost eight weeks and had halted construction at the power plant.

They had questioned the way in which their year-end bonuses were calculated, claiming this should have been done on the basis of a six-day week, and not a five-day week.

Workers also complained that employees who lived in the area were paid less than workers who came in from Johannesburg.

They went back on strike on Tuesday afternoon, after employers failed to deliver on the obligations stipulated in the PLA.

Numsa said part of the agreement to end the strike was that workers get a once-off payment of R2000, and a month's salary.

They would also get an interest-free loan to the value of 90-hours of work, which they could pay back over six months.

Some of the workers were paid on Tuesday, but others were not.

Numsa said workers had since been paid the R2000 and had returned to work.

Gigaba said Eskom had to play a bigger role in mediating between the contractors and the workers at the power station.

"Clearly, Eskom must exercise a more active role in the management of these projects, and ensuring that they constantly mediate the dispute between the workers and employers," he said.

He said unions and employers had to bear in mind the need for labour peace, higher productivity, the strategic importance of the project and the urgency to complete it.