Johannesburg - Metalworkers' trade union Numsa on Thursday called for an independent investigation into alleged collusion by construction companies at the Medupi power station in Limpopo.
"Those companies need to be dealt with very harshly," Numsa general secretary Irvin Jim told reporters in Johannesburg.
The time had also come for government to think about a state-owned construction company to curb collusion and unlawful expenditure.
"If we don't do that then we are open to looting.
"We know they colluded and made money.
"Instead of taking them to jail it was a slap on the wrist by the Competition Commission," Jim said.
The Competition Commission announced last month that 15 construction firms had been fined R1.46bn for collusive tendering involving projects for the 2010 Fifa World Cup.
The projects were estimated to be worth about R47bn and took place between 2006 and 2010.
Project
Jim claimed that companies and other individuals involved at Medupi were trying to sabotage the project to make more money.
The union had heard of managers at the plant leasing their houses to workers and stood to gain more if the project was extended.
"There are allegations of a bomb that was found last week.
"What was the intention of the bomb?
"Was it to blow up the work that has already been done?
"What we are saying is it is time for Eskom to make sure that this mega project is safe," Jim said.
He called on the power utility to hold the contractors accountable and to keep them on a tight leash to ensure completion of the project without glitches.
"Eskom must not to allow these companies to make mistakes.
"They have not demonstrated that they are in favour of making sure we deliver on the promised deadline."
Jim said the trade union was concerned about the planned retrenchment of 2000 workers at the plant as this would hamper the project and might even result in the new deadline not being met.
Eskom announced on Monday that Medupi would not be able to deliver its first power to the national grid in December 2013 as scheduled.
The first unit of Medupi had been scheduled to deliver 800MW by the end of December, but Eskom said this would be postponed by about six months.