Britain’s biggest energy provider is raising the cost of charging electric cars in a fresh blow to drivers.

Octopus Energy said it will restrict its cut-price electric vehicle (EV) tariff from the new year, in a move that could cost some drivers hundreds of pounds annually.

It comes amid rising household electricity prices and as EV owners face new taxes that have put the Government’s net zero targets under pressure.

Octopus’s Intelligent Go tariff is Britain’s most popular EV plan, used by 260,000 drivers – or more than one in 10 EV owners. It allows motorists to enjoy cheap household energy when their car is charging, significantly cutting the cost of running an electric vehicle.

However, the company has written to customers telling them that discounted charging will be limited to six hours a day from January.

Limiting use of cheap charging rates is likely to drive up energy bills, since motorists will pay peak rates roughly four times higher when they wish to charge their car for longer periods.

It makes Octopus, which has almost eight million customers, the latest energy supplier to raise the cost of charging at home after rival supplier Ovo doubled EV charging prices earlier this year.

The changes have led to a backlash from customers, with one user on social media branding them “a complete mess” and saying people would move to other suppliers. “What’s the advantage of staying with Octopus now?” another wrote.

Energy companies have raced to attract EV drivers with specialised tariffs that offer cheap charging during off-peak periods.

The tariffs have made running electric cars significantly cheaper than petrol, and served as a key selling point to encourage sales of expensive plug-in vehicles, since public charging costs several times more.

Octopus’s changes could more than double the cost of fully charging cars with large batteries, which can take more than 10 hours to charge from empty to full.

The cost of refuelling some versions of Tesla’s Model Y, Britain’s most popular electric car, from 5pc to 100pc would rise from around £5.50 to more than £13.

A series of recent changes have made driving an EV more expensive even as sales continue to sit below government targets. This year electric car owners lost a road tax exemption, and pricier cars are now subject to a “luxury car tax”.

In last month’s Budget, Ms Reeves said that EV drivers would have to pay 3p a mile from 2028, adding an average £255 to the cost of driving each year. Campaigners have said the tax threatens to curb rising EV sales, while the Office for Budget Responsibility has said the policy will cut sales by 440,000 over the next five years.

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Octopus told customers that four in five charging sessions on the tariff already take fewer than six hours and that it hoped the changes encouraged them to charge daily in smaller bursts, allowing it to more easily manage demand.

The company has also said that some customers are using technical “workarounds” to slow down charging speeds and enjoy hours of cheap electricity, since a whole household benefits from lower rates while the car is being charged.

Drivers who regularly cover hundreds of miles, and so need to charge for long distances, face being hit by the change. A full charge every two weeks could cost drivers hundreds of extra pounds a year.

An Octopus spokesman said the changes “make sure the tariff continues to offer great value for everyone” and were not linked to wider energy market conditions nor an attempt to move drivers to other tariffs.

Ofgem recently announced that energy prices would rise in January despite forecasts that bills would fall.

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