The ‘big six’ provider has committed not to increase its standard variable energy prices until at least April 2017.

It follows similar recent moves by both SSE and British Gas.

An E.ON spokesperson said: “We have been working hard behind the scenes to make sure we could make a commitment to our customers before Christmas that we would not increase our residential standard energy prices until at least after winter. We are pleased to be able to offer that reassurance to our customers.

“We will continue to engage our customers on a wide range of topics including making them aware of their different tariff choices, helping them to use no more energy than they need and getting Smart meters into homes across Britain.”

Citizens Advice urged large suppliers to hold off raising standard tariff rates this winter, adding that those to see the price freeze are still paying a premium.

Gillian Guy, chief executive of Citizens Advice, said: “A winter price freeze will provide some relief to people paying a steep price for the standard tariff.

“Energy customers on the standard tariff are already paying a premium – their bills are as much as £380 more than for those on cheaper fixed deals.

“British Gas and SSE have led the way by promising not to raise prices – we now expect other big firms to do the same. Larger energy firms didn’t pass on savings when wholesale prices were going down, so those savings can be used to support customers now that wholesale prices are rising and the pound is down.”