"In its letter to customers, Genesis says the 2.7% increase is designed to help the SOE 'make an acceptable return on our assets'.
"If that's the case now, when all Kiwis own the company, how much more will prices go up when shares in the company are sold to so-called mum and dad investors?
"Those investors would initially be New Zealanders wealthy enough to invest. Inevitably, they would on-sell, probably to foreign investors, when they received an offer they felt they could not refuse, Mr Goff said.
Prime Minister John Key announced last month the Government was seeking advice from Treasury on the partial sell-down of shares in Genesis, Meridian Energy, Mighty River Power and Solid Energy.
Mr Goff said the further the three power companies became divorced from New Zealand ownership, the more pressure companies like Genesis would feel to make an "acceptable return", which was anything but in the interests of the vast majority of consumers.
Standard and Poor's rating services said, if the Government was to proceed with selling minority stakes in the three electricity generators, there was unlikely to be any effect on the rating uplift that applied to the ratings on those companies.
"The current rating uplift primarily reflects our view of the 'important' role of the three companies to the New Zealand economy," primary credit analyst Richard Creed said.
Also, the proposed sales and timing were not definitive and the Government was expected to retain majority ownership and control of the three businesses.
Nevertheless, besides the credit profiles of the entities, the factors that could affect S&P's view of Government support included: the level and identity of minority shareholding; the form of sale; the ensuing board composition and corporate governance; and the financial policies of those companies under a revised share ownership, Mr Creed said.
