Broadband customers are being misled by some broadband comparison sites over the capabilities of their connections, according to Virgin Media.
A new statement represents the second time one of Britain's leading broadband ISPs has questioned the validity of speed tests advertised on many websites.
As part of a campaign to alert customers to the possibly inaccurate data which some speed tests are said to produce Virgin Media has shared information with the Internet Service Providers Association and Ofcom.
"Many of these sites profess to be 'experts' and some even generate sales from broadband providers so I am sure that consumers would find it alarming that they are unable to accurately represent speeds accurately," explained Jon James, Virgin Media's Director of Broadband.
"We are pleased, however, that our campaign has kick-started most of these sites into action and we will continue to work with those that are non-compliant to get them to the standard that they need to be."
Virgin Media says it started the campaign to ensure that customers would get a true reflection of its 50Mb service when testing the high-speed cable broadband connection.