The company recently announced it would increase prices by more than 9% on July 1.
Increasing generation and supply costs were blamed for 6% of the increase.
The rest, 3.2%, was linked to the Emissions Trading Scheme (ETS).
Mercury Energy announced a 3.3% ETS increase in May.
Both imposed a levy less than the up-to 5% increase Climate Change Minister Nick Smith said the Government expected the ETS to add to electricity prices, but Ms Curran warned it might only be the start.
Most other companies waited to see how the ETS would affect wholesale electricity prices before adjusting their tariffs: Contact Energy was one of the "first cabs off the rank", Ms Curran said.
She was worried the ETS, and October's GST increase, would become "an excuse" for some companies to increase charges that far outstripped government projections.
The Government needed to send a clear signal that it was watching prices and would launch an inquiry if prices rose more than necessary.
"It is up to the Government to scrutinise power companies ... We are saying, do something."
Energy Minister Gerry Brownlee has stopped short of criticising Contact's price review, saying instead Dunedin consumers should shop around in the city's competitive electricity market.
A spokesman said Mr Brownlee had made it clear to the retail industry that he did not want unreasonable price increases, and that the Electricity Commission should continue to monitor the deregulated market.
It would be premature to call for an inquiry into prices when most companies were still considering the effect of the ETS, he said.
Most companies in the Dunedin market were holding on increases, suggesting competition was working, he said.
