A report by power supplier Npower, claiming bills will rise due to higher energy distribution costs, has been dismissed by regulator Ofgem as "misleading".
Npower, one of the UK's big six suppliers, said the report was designed to "shine a light" on company costs.
In it, the company argues that energy suppliers make small profits and have little control over customer bills.
But Ofgem said that some of the data used was "incorrect and misleading".
In its analysis, Npower said the cost of transporting gas and electricity - so-called network costs - would increase from £295 per customer to £314 between 2015 and 2020.
But Ofgem, which regulates that side of the industry - and sets the price controls - said those figures were wrong.
NPower said bills are high because British houses waste so much energy
Last month, the company was fined £3.5m by Ofgem, for breaching sales regulations. Based on the line above should be to spend their fine investing in energy conservation.