Gas price comparison websites have become increasingly popular

Regulator Energywatch gave Uswitch five days to change how it displays information or lose its accreditation.

Uswitch is one of a number of firms that have been told they must propose changes to their website, having failed initial accreditation tests.

The firm said it strongly objects to claims that it is misleading customers.

Energywatch's review was prompted by concern that some price comparison websites have distorted results to favour firms paying higher commissions.

Energy comparison websites allow customers to search for the cheapest suppliers and possible savings they could make.

If they switch supplier the website will often make a commission.

'Consumer confidence'

"Our primary objective is to do what is best for consumers," a Uswitch spokeswoman said.

"We have lobbied Energywatch to review the code and implement an audit process for price comparison services for the past three years."

Uswitch will hold talks with Energywatch in the next few days and says it is confident the firm will be fully compliant.

"We welcome any changes that increase consumer confidence, and provide greater transparency in the energy industry overall," a spokeswoman said.

Energywatch is in the final stages of auditing changes made by energy comparison websites so that they can be accredited.

"This will be completed within a week or so and we will then announce the bodies that are compliant with the code," said Energywatch director of campaigns Adam Scorer.