Last month the commission said it was imposing price control on the gas pipeline services of Vector and fellow energy network company Powerco. It ordered Auckland-headquartered Vector to drop its average prices by 9.5% and New Plymouth-headquartered Powerco to cut its average prices by 9% from October.

Vector has since told the commission it was proposing to raise residential consumer prices by 5%, cut small business charges by 5%, and cut prices for medium-large commercial and industrial users by various amounts.

But Reuters reported commission chair Paula Rebstock as yesterday saying that approach did not apply a price decrease across all customer classes, as the commission wanted.

The commission would intervene next week if necessary to amend its original control order, which would allow Vector to keep its current prices until November, but after that it would impose prices cuts of 10.4%.

In July energy minister Trevor Mallard recommended the commission implement price control for Vector and Powerco after it found the two were earning "excessive" after-tax returns on capital of 12.7% and 13.5% respectively. Mallard said Vector pipeline customers should see an average drop of 18.5%, and Powerco pipeline consumers a 12.2% decrease, from price control.

But former Powerco boss Steven Boulton - who now heads Powerco parent company Babock & Brown Infrastructure in Sydney – slammed the commission's decision, saying the NZ energy industry desperately needed an independent third party to review the decisions of such regulators.

Vector chief executive Mark Franklin said then the new regulations affected only a part of group business, which included NGC Holdings, but he objected to the principle of price control.