A spokesman for Powergen, whose prices soared by 17.6% last year, and will now rise again, said the company had held off making the latest increase for as long as possible. He added: 'It comes as a direct result of unparalleled rises in wholesale costs which are affecting all energy suppliers, many of which have already announced price increases. Wholesale costs have risen 39% for electricity and 49% for gas in the last six months.'