British Gas is the latest supplier to increase prices. E.ON, EDF Energy and Npower all made similar announcements last week.

The hike means 3.5 million British Gas customers will pay an extra £117 a year on average, taking the cost of the average bill to £1,254.

Suppliers have raised prices in line with an increase to the energy price cap announced by the regulator Ofgem earlier this month.

Commenting on the British Gas news, Stephen Murray, energy expert at MoneySuperMarket, said: “The UK’s biggest energy supplier has the largest number of customers on standard variable tariffs and today’s announcement means it is instantly adding a cumulative £409m to those customers’ bills.

“There’s a lot of noise about the energy price cap at the moment and how it’s supposedly delivering a fairer price on energy bills and protecting people from getting ripped off by suppliers.

“But with the level of the cap set to rise by £117 at the start of April, that couldn’t be further from the truth and there’s really only one way for people to bring their bills down – and that’s by switching.”

Biggest energy price rise

When the new cap kicks in on 1 April, eight million households will face one of the largest energy price rises to happen on a single day, according to Richard Neudegg, head of regulation at uSwitch.

“With more suppliers expected to raise their prices to the new cap, over half the energy customers in Britain could affected. But they have a chance to escape being part of the grim statistics – instead they can save hundreds of pounds by switching away.

“Nine in 10 energy deals available today are cheaper than the new cap will be. Now is the time for energy customers to grab one of those cheap deals and find themselves up to £324 a year better off.”