Waitrose managing director Mark Price has hit back at rival Marks & Spencer’s claims that a typical basket of products in its shops is cheaper than the John Lewis Partnership-owned grocer.

Price told Retail Week: “It’s hugely flattering that M&S is targeting us in their advertising, and we’re pleased they are using us as a benchmark for quality and value.”

M&S launched a price comparison ad campaign this week targeting Waitrose’s Essentials range. It is the first time M&S has adopted the tactic against its close competitor.

The ads, under the strapline, “Price checked against Waitrose Essentials. Quality checked by M&S” promote the M&S Wise Buy range.

An M&S spokesperson said: “Within a basket of 1,200 products M&S is typically 2% cheaper than Waitrose - it’s only right our customers hear this message.”

However, Price said: “We benchmark 200 Wise Buy lines with Essentials and we are around 6% cheaper, and on a further 600 comparable lines we benchmark, we are around 5% cheaper.”

TNS data shows Waitrose’s market share is now 4%, helped by Essentials. Analysts say M&S has been hit by Waitrose’s advance.