The heads of three stated-owned energy companies earmarked for partial sale have downplayed opposition fears about the sell-offs.
Representatives of Mighty River Power, Genesis, and Solid Energy appeared before Parliament's commerce select committee on Thursday.
Chief among MP concerns was the prospect of partially privatised companies raising power prices in a manner that would never have been possible under 100% government ownership.
Mighty River Power chief executive Doug Heffernan said the company operated in a competitive market and this was unlikely.
He also suggested that better decisions may have been made if it had been partially privatised sooner, including getting rid of its landfill assets earlier than it did, and limiting its spending on upstream gas.
Solid Energy's John Palmer said its multi-billion dollar expansion plans can not be funded by the taxpayer alone, and if it were up to him he would have listed the company last year.
Earlier Mighty River Power chair Joan Withers said a partial sale was a natural evolution and in the best interests of the company.
Ms Withers was questioned by Labour MP Clayton Cosgrove.
He asked if the board had formed a view on whether it was a smart move to sell a minority stake in such a highly profitable company.
Ms Withers said it was in Mighty River Power's best interests as day-to-day scrutiny of the market and analysts means there is more external assessment of a company's performance.