Customers on EDF’s standard variable tariff paying by direct debit will see their dual-fuel bill increase by 12 per cent to £1,277.

It comes after the regulator Ofgem confirmed the price cap would go up by £139 from 1 October 2021.

Ofgem said the increase is driven by a rise of more than 50 per cent in energy costs over the past six months with gas prices hitting a record high as the world emerges from lockdown.

The price cap offers a safety net for customers who haven’t switched suppliers or tariffs by limiting how much suppliers can charge for a standard or default tariff each year.

Ofgem adjusts the price cap twice a year based on the latest estimated costs of supplying energy.

In April, the cap was increased by £96 to pre-pandemic levels of £1,138 for default tariff customers.

Tom Lyon, director of energy at energyhelpline.com, said: “This price rise could not come at a worse time for millions of EDF Energy customers who have already seen their bills increase once this year and will now have to suffer a further £139 price hike to power their homes.

“Although Ofgem sets the rate of the price cap, there is no requirement on energy suppliers to raise prices on standard variable tariffs to the highest level possible. And given we are about to enter the coldest part of the year, any increase in energy bills will be an even bigger blow to hard-pressed customers.

“We have already started to see the cheapest tariffs being removed by suppliers, and with every passing week the best value fixed deals are going up in price. Incredibly, since the price cap level was set just ten days ago, wholesale energy prices have continued to increase sharply and the trend of the lowest priced deals being replaced by more expensive ones could be set to continue.”

Philippe Commaret, managing director of customers at EDF, said: “We know a price rise is never welcome, especially in tough times. In 2020, prices for our standard variable customers fell by an average of £100 a year, and we’ll cut prices again as soon as we’re able.

“As Ofgem has explained, it is global gas prices that have caused the unprecedented increase in wholesale energy costs and as a sustainable, long-term business we must reflect the costs we face.”

According to energyhelpline, households can save as much as £200 a year by switching to a cheaper tariff.

They can also fix their bills for 12 months to avoid future price rises.