ScottishPower’s 7% price rise for gas and electricity kicks in today – making it the most expensive supplier for standard tariff customers.

The new move will see the average household bill for a dual fuel customer go up from £1,349 to £1,368, which is expected to affect around 2.3 million households.

A ScottishPower spokesperson said: “We work hard to protect our customers and we regret that we had to announce a price increase. We reduced our gas prices in February but for most of the year we have been absorbing increased costs especially for transporting gas and electricity to our customers’ homes and the cost of delivering energy efficiency programmes. However, we remain committed to continuing to work with the Government to help reduce the amount of energy we all use and help our customers reduce their energy bills over the longer term.

“We will continue to try to help our customers by offering competitive products and also through the commitments we have made to help our vulnerable customers through this winter.”

Five of the ‘Big Six’ suppliers have increased their energy prices this winter except E.ON which has promised not to raise prices until April 2013.

Ann Robinson, Director of Consumer Policy at uSwitch.com said: “The good news is that in real terms this increase is the smallest seen so far by the Big Six. The bad news is that it still leaves ScottishPower customers sitting on the most expensive standard tariff on the market – and that means they are paying far more for their energy than they need to.”

Ms Robinson is urging consumers to switch suppliers and take advantage of free or low-cost home insulation offers available to cut energy use.

However, she adds people can’t afford to hang around: “The cost of the most competitive energy plans is creeping steadily upwards while competitive home insulation offers are gradually disappearing ahead of an end-of-December deadline. These two steps will help you to save money so I would urge consumers not to miss out.”