Power prices are soaring "out of control" on the eve of winter, with some companies hiking prices up a "staggering" 9 per cent in one month, Labour says.
The price increases were "totally unreasonable" for Kiwi families, energy spokesman David Shearer said.
Energy Minister Simon Bridges earlier predicted power prices to rise about 2.4 per cent over the six months from February to August 2014, but Shearer claimed many regions had exceeded this in just one month.
"In Christchurch, some power company prices have jumped over six per cent in just a month. Other companies have hiked their prices up a staggering 9 per cent in a month," Shearer said.
"It is simply not fair for Kiwis to face those sorts of bills."
Shearer based his assertions on data from the PowerSwitch website, which tracks national power prices.
The latest PowerSwitch figures show significant price rises from March to April across the country.
Christchurch appears to have been hit the hardest, with two companies, Nova and Powershop, recording price increases of more than 9 per cent for the month.
However, Bridges discredited Shearer's claims as "scaremongering".
The majority of New Zealand's power retailers increased their prices on April 1 and the Powerswitch data "captures that increase", Bridges said.
A competitive market was the best way to put downward pressure on power prices and New Zealand's electricity market was "the most competitive it has ever been" thanks to the National Government reforms, Bridges said.
In Christchurch, Powershop prices climbed from an average $2206 to $2409 between March and April - an increase of 9.2 per cent.
Powershop chief executive Ari Sargent said the increase was caused by several factors.
It was also being affected by the third year of the approved Transpower price increases to fund national grid upgrade projects.
Christchurch was bearing the brunt of the increases because of additional funding needed for earthquake recovery work, he said.
Shearer believed the latest increases would "dwarf anything Transpower could pass through".
"The electricity market is clearly broken," he said.
- The Press