New Zealand First leader Winston Peters says power prices will go through the roof if the National-led Government goes ahead with its plan to partially sell some of the country's state assets.
Mr Peters says the cost of power has gone up at least 10% this winter and electricity companies are gearing up for further increases.
He told a Grey Power meeting in Wainuiomata, near Lower Hutt, on Wednesday that those companies will get a far greater price per share in an asset sale if they can increase prices and demonstrate a better return to private investors.
Mr Peters says rights to water from lakes and rivers to generate power could also be sold under the asset sales.
He says no one will buy a power station if they do not have a guaranteed water right.