Grocer Morrisons is considering complaining to the Advertising Standards Authority (ASA) about Tesco’s Price Promise.

Morrions claimed its rival’s Price Promise “doesn’t correctly compare the price of Tesco products with Morrisons products”.

It follows Sainsbury’s decision to formally complain to the ASA over Tesco’s Price Promise last month because of what it called “misleading” comparisons.

The Bradford-based grocer believes the Tesco Price Promise is “misleading customers into thinking that Tesco will always compensate them if they shop at Tesco but Morrisons is cheaper”.

Morrisons said it has “checked these price comparisons and found that Tesco is unable to make a comparison in many cases and lists Morrisons’ prices as ‘not available’. This may be because Tesco can only check Morrisons’ prices manually through mystery shopping exercises”.

The Price Promise works by comparing a shopper’s basket with prices from other supermarkets.

Morrisons said the prices missing from Tesco’s Price Promise calculation are often own-brand fresh products.

Morrisons customer director Crawford Davidson said: “Tesco’s Price Promise provides a false assurance that it will compensate customers when Morrisons is cheaper, which it mostly is.

“Customers expect Tesco to do this properly. If Tesco can’t accurately collect prices of its rivals and make trustworthy comparisons, then it should not be making this so-called promise.”