The Electricity Authority is investigating claims New Zealand's largest electricity generating company manipulated the electricity market to maximise its own profits.
The case concerns an electricity price spike early this month, during which wholesale prices shot up for two short periods from a norm of $60 to $70 a megawatt hour to an average of $230.
A small power retailer, Electric Kiwi, said Meridian Energy withheld cheap electricity from the South Island to drive up the price.
The authority said it was continuing to gather and process information as part of an investigation of the claim by Electric Kiwi.
In an earlier statement, Meridian insisted it had done nothing wrong. It said it was wrong to say the company had removed low-priced offers and replaced them with high-priced offers.
The company said it would assist any inquiry by the authority.