The website compares extended warranties for a wide range of domestic electrical goods from household names such as Argos and Dixons.

Providers on the site cover around 75% of UK extended warranty sales, the OFT said.

However, the consumer watchdog refused to include John Lewis on the website, because the company includes extended warranties as part of the total price for anyone buying an electrical good.

Andy Street, John Lewis managing director told the Daily Telegraph: “The OFT is supposed to exist to defend consumer interest. This is a clear case where it is acting in exactly the opposite way.

“To be told that we should increase prices simply to be included, it’s irrational, it’s madness.”

The new website follows an OFT study last year, which revealed various concerns that could mean consumers are not getting the best value for money.

Among them, the watchdog found that only around a quarter of consumers shop around for extended warranties and when buying an extended warranty at the same time as an electrical good, shoppers do not have enough relevant information to make an informed decision about whether the extended warranty is value for money.

Ann Pope, OFT senior director in services, infrastructure and public markets, said: “Millions of extended warranties are purchased by UK consumers, so this site will provide a much needed tool to make it easier for them to choose the best deal. We urge consumers to shop around before they buy an extended warranty with their electrical goods to make sure they are getting value for money.”