E.On is the fourth of the six big energy companies to put up its gas and electricity prices.
The company has announced that it will raise prices from 13 September by 18 per cent for gas, and electricity will go up by 11 per cent.

E.On has five million domestic and business customers in the UK. Like the other firms that have raised prices, it has blamed the increases on the 30 per cent rise in wholesale energy prices this year.

'Uncertain times have had a huge effect on wholesale prices, with events in Japan and Libya all having a dramatic effect on gas and power prices in a relatively short period of time,' said Graham Bartlett of E.On.

E.On has five million domestic and business customers in the UK. The BBC reports that this is the second price for their customers who saw a 9 per cent increase in electricity prices and a 3 per cent rise in gas prices on 4 February 2011.

The price comparison service Uswitch said this meant the company's bills had risen by £232 or 22 per cent this year, pushing them up from £1,061 a year to £1,293.

Paul Green of Energyhelpline told the BBC, 'even though this price rise was fairly predictable, the scale of it will stun E.On customers. It's now surely only a matter of time before EDF and Npower fall into line'

In July, British Gas was the first energy company to announce that it would be increasing prices by 18 per cent for gas and 16 per cent for electricity. Scottish & Southern Energy (SSE) then followed suit saying the average gas bill will increase by 18 per cent and 11 per cent for electricity. Swalec, who are part of SSE will also be increasing prices in line with SSE.

Mike O'Connor, the chief executive of Consumer Focus, added: 'Wholesale costs are around a third lower than their 2008 peak, yet consumer prices have reached an all-time high. Ofgem has said it is prepared to refer the energy market to the Competition Commission if necessary. That is welcome, but the regulator must be prepared to act if it can't say for certain whether prices are fair.'