Energy companies have ramped up their charges since the Brexit vote, putting as much as £105 a year on the cost of their fixed-rate deals.
With the UK a net importer of energy, the falling pound has pushed up the suppliers' costs, and this increase is being passed on to consumers.
The rise was predicted by the Remain campaign, with energy secretary Amber Rudd forecasting price hikes of £20 per household in the event of Brexit. And it now seems it may be worse than that.
According to price comparison site uSwitch, fifteen suppliers have replaced their cheapest fixed rate tariffs with more expensive plans in the last month, with an average increase of £38.
Extra Energy has raised its prices by £105, Sainsbury's Energy by £94, OVO Energy by £63 and First Utility by £48. Twelve of the 15 suppliers have upped their prices since the EU referendum on 23rd June.
It's a reversal of the previous trend.
"For nearly three years, wholesale gas and electricity prices have been falling, leading to cheaper and cheaper fixed term deals for consumers," says uSwitch.com energy expert Tom Lyon.
"But with concerns about future UK energy supply, the impact of Brexit and a weaker pound, we are starting to see some suppliers increase the price of their cheapest deals."
The wholesale prices of gas and electricity had been falling for more than two years, but both began to climb in the second quarter of this year.
This, according to independent price reporting agency ICIS, is due to future energy supply concerns, market uncertainty following the UK's EU referendum result and the falling value of the pound, which makes energy imports more expensive.
With many observers expecting sterling to slip still further in future, uSwitch advises customers to consider a fixed-rate deal to protect against any potential future price hikes.
"There are still some very competitive deals on the market, offering significant savings against the average big six standard variable plan," he says.
Npower, for example, has this week launched its 'Online Price Fix August 2017′ tariff at £786 a year; while First Utility is offering a three-year fixed deal - FU First Fixed June 2019 v2 plus - priced at £999 a year.