Scottish and Southern Energy (SSE) has announced that its customers' gas bills will increase by 12.2 per cent on average from the new year onwards.
Electricity bills will rise by 9.4 per cent on January 1st 2007, the firm said, following last week's admission that it would be forced to raise prices.
The last three years have witnessed increases in energy bills across the board from all energy suppliers, but SSE today insisted that it had made "fewer price increases than all the other major energy suppliers".
But Alistair Phillips-Davies, energy supply director at the utility, today admitted: "The consequences of three years of high wholesale energy prices are, however, still being felt.
"Even after these latest increases take effect, our gas prices and dual fuel prices will still be the lowest in the country. If, as everyone hopes, falls in wholesale energy prices continue and are sustained, we will move as quickly as we can to reverse the price rises of recent years," he added.
Unprecedented wholesale gas prices, mainly due to a declining supply from the North Sea, have forced suppliers to raise their own tariffs, but consumers are now calling for reductions in wholesale gas over the last six months due to new continental supplies to be reflected in their bills.