This hike will see the supplier fall to the bottom of the energy best buy tables and behind Britain’s ‘Big 6′; suppliers, according to comparison site uSwitch.com.

Existing customers are said to be unaffected by this price increase.

Tom Lyon, energy expert at uSwitch.com, said: “Co-op Energy has become a familiar and welcome sight in the best buy tables.

“Today’s move will be a blow as it has been offering consumers a great alternative to the traditional big six, while still being a brand that consumers know and trust.

“However, true to its word, this price hike will not affect existing customers, but it will hamper its ability to attract new customers any time soon. Hopefully this will just be a short-term blip as it is good for consumers and for the market to see a wide-range of suppliers competing hard.”

Co-op says on its website ‘We’ll rarely be the absolute cheapest because we don’t intend to offer short-term low prices just to win your custom.

‘Instead, we’ll take a long-term approach by being consistently amongst the cheapest. We think consistently low prices and guaranteed peace of mind are what people want; that way you won’t ever feel the need to switch again.’

ScottishPower has also launched a new online plan called Online Energy Saver 21, costing £1,164 a year, making it the third cheapest supplier on the market behind SSE and First Utility.

Lyon added: “And this is why smaller suppliers and new entrants are so important – not only do they mean that consumers have a better choice of tariffs from a broader range of suppliers, but they also force the big six to slug it out on the competitive field.

“With the average household energy bill now hitting £1,352 a year and winter fuel bills on their way, I would urge consumers to take advantage and reduce their bills by shopping around for a better deal today.”