E.ON today became the fifth of the UK’s “Big Six” energy suppliers to announce a hike in electricity and gas prices.

The group, which has many customers in East Anglia, said its standard prices would rise by 9% for electricity and 3% for gas with effect from February 4.

For an average customer on a “dual fuel” deal covering both gas and electricity, the increase will add an extra �58.40 to bills over a full year.

However, households on E.ON’s WarmAssist deal for vulnerable customers and others on capped or fixed rate deals will not be affected by the increases.

E.ON blamed the move on rising industry costs, particularly wholesale energy prices – the prices which energy retailers pay for the gas and electricity they supply to end users – which it said had increased by 35% since last spring.

Graham Bartlett, managing director of E.ON’s Energy Solutions business, said: “It’s been over two years since we last increased our prices, and, unlike other companies, we held off from increasing them during the incredibly cold temperatures we saw in late November and December.

“But we now have no option but to make this change due to increases in the prices we pay for gas and electricity, although our customers won’t actually see the increases until next month.

“In fact, we’re even protecting our most vulnerable customers from this increase, with most unaffected until the winter’s over, and looking to help everyone where we can.”

Other “Big Six” suppliers to have raised their prices in recent weeks including British Gas, npower, Scottish & Southern and Scottish Power.

The last to make its move is EDF, which has promised to hold its prices until March, although, whereas E.ON has not lifted its prices since August 2008, EDF previously raised its domestic prices as recently as last October

German-owned E.ON has a relatively large customer base in the East of England as a result of the acquisition by its UK arm, then known as Powergen, of the TXU business which included retail arm of the former Eastern Electricity.

Although customers are able to switch between suppliers in search of a better deal, those in the East of England who have never bothered to change will be supplied by E.ON.