Asda has launched a prime time TV advertising campaign, shown during Coronation Street on ITV and backed up online, claiming that it has the lowest fuel prices of any retailer.

Quoting ‘Experian All Star card’ as its source it claims, based on a comparison of weekly national average prices from 29 May 2011 to 22 June 2013, that ‘week in, week out’, Asda consistently had the lowest fuel prices of any fuel retailer.

It adds that it is using a “comparison of weekly national average petrol prices and weekly national average diesel prices at Morrisons, Tesco, Sainsbury’s, Esso, Jet, Shell, Murco, BP, Texaco, Total and Asda across Great Britain. Prices independently checked and validated every week. Average prices may exclude the effect of promotional discounts linked to individual purchases.”

Arthur Renshaw, UK and Ireland manager of Experian Catalist, which monitors daily transactions at petrol stations accepting the Allstar fuel cards, said his company would not officially endorse such claims by any company.

However, any company subscribing to its data was free to carry out its own interpretation of the figures, and that company would then have to justify its interpretation were there to be a challenge to any claims it made.