The UK's top six energy firms - British Gas, Npower, E.ON, EDF Energy, Scottish Power and Scottish and Southern Energy - collectively spent a record £58.5m on marketing from January and June, compared with £46.4m over the same period last year, according to Nielsen Media Research.
According to comparison site uSwitch, the average increase in the cost of gas has been 28%, while electricity prices have shot up by 20%.
The escalation in marketing spend has been criticised by groups concerned by the price of fuel. A spokesman for the Child Poverty Action Group, said: 'Pumping up the marketing budget while cutting social assistance to these households is adding insult to injury.'
Adam Scorer, a spokesman for Energywatch, noted a correlation between price hikes and marketing activity. 'At a time when bad deals are set to get even worse, companies will make sure that consumers know about the limited competition in the market,' he said.
EDF defended its spending hike, saying energy had 'moved from being a commodity to being a brand', making marketing more important.
The industry regulator, Ofgem, declined to comment, but said it was conducting an investigation into the commercial activities of energy firms and would publish its findings at the end of next month.