Nearly 10 million households are at risk of overpaying for their energy bills if they do not act.

Millions of UK households are being told to send meter readings to their suppliers, as a new 10% price rise takes effect today.

Energy bills are set to rise by £149 for the average household in October after Ofgem announced it would be raising its energy price cap.

The new price cap figure will be £1,717 from October 1, up from £1,568 previously.

The cap does not set the maximum a household will pay for their energy but limits the amount providers can charge them per unit of gas or electricity, so those who use more energy will pay more.

Those households on a standard variable tariff (SVT), as opposed to a fixed deal, and who do not have a smart meter, should submit their electricity and gas readings to their supplier as soon as possible if they have not already done so, to ensure any energy they have used before October 1 is not inaccurately billed at the higher prices.

Suppliers who have not received meter readings base their bills on estimated usage, meaning households could be overpaying, while others may not be paying enough.

Ofgem said rising prices in the international energy market, because of heightened political tensions and extreme weather events, were the main driver behind the decision.

Millions of pensioners are also facing a winter with less support, after the new Government decided to scrap winter fuel payments for those who do not receive pension credits or other benefits.

About 10 million pensioners will miss out on the payments of up to £300 this year.

Ofgem chief executive Jonathan Brearley has urged people to “shop around” and consider a fixed-rate tariff that could save money, adding that the regulator was working with Government, suppliers, charities and consumer groups to do “everything we can” to support customers.

Citizens Advice has said it was particularly concerned about households with children and young people and those on lower incomes, who were most likely to struggle with their heating costs.

Comparison site Uswitch.com calculated that the average household on an SVT is expected to spend £135 on energy in October compared with £55 in September, because of a combination of higher rates and increased usage at the start of autumn.

Elise Melville, energy spokeswoman at Uswitch, said: “There are plenty of fixed energy tariffs that are cheaper than the October price cap and more are coming on to the market as competition increases.

“With the long-term outlook for energy prices uncertain, it’s worth taking the opportunity to lock in lower rates before the start of winter.”