Sainsbury’s is to appeal the Advertising Standards Authority’s decision that Tesco’s Price Promise claims are fair and is considering taking the fight to the courts.

Sainsbury’s complained that Tesco’s advertising was misleading customers by claiming its own-brand products were cheaper as Sainsbury’s products are superior quality. However, the ASA threw out the complaint last week.

The grocer will contact the ASA independent reviewer Sir Hayden Phillips to appeal the decision as early as today.

However, senior figures within Sainsbury’s want the grocer to take the fight “as far as it can” in order to get a satisfactory resolution, according to The Mail on Sunday. Sources said the grocer could press ahead with a legal claim without waiting for Phillips’ review.

A Judicial Review could overturn the ASA ruling and would also allow a broader investigation into the increasing value shoppers are placing on food provenance. 

Sainsbury’s argues that Tesco should not be allowed to compare Fairtrade bananas with non-Fairtrade bananas, or its British-produced Basics ham with Tesco’s Everyday Value ham, which is produced in an unspecified country in the EU.

Sainsbury’s claims such comparisons are “misleading and unfair”.

It is understood the grocer has been bolstered by support both from customers and the National Farmers’ Union to launch the appeal.

Sainsbury’s launched national press advertising last week to highlight the differences between its products and Tesco’s.

The ads ran under the strapline ‘Same price, different values’ and read: “They cost exactly the same. But it’s what you can’t see that makes the difference.”

Fellow rival Morrisons is also in talks with Tesco over prices it believes have not been fairly matched.