Energy firm E.ON said it will increase electricity and gas prices for the majority of its residential customers in the UK.
Standard prices will rise by 9% for electricity and 3% for gas from 4 February this year.
The company said that the move comes as a result of rising industry costs, in particular wholesale energy prices which have increased by 35% since last spring.
This is said to be the first increase in prices made by E.ON since August 2008, with the company having cut prices three times since then.
E.ON energy solutions business managing director Graham Bartlett said that the company now has no option but to make this change due to increases in the prices it pays for gas and electricity.
Other energy suppliers such as British Gas, Scottish and Southern Energy (SSE), npower and Scottish Power have already hiked prices in the UK.