The latest investigation centres on pre-budget offers by the chain of leading brands of beer, wines, spirits and champagne at cost price.
According to Foley, customers using a Tesco Clubcard could claim a further 10% discount, leaving the company in breach of the Groceries Order.
A spokesman for Tesco said it had taken legal advice and believed the offers were within the law. Foley said she would get her own legal advice and had directed inspectors to examine the invoices for the drinks advertised which included Guinness, Heineken, Baileys, Hennessy, Jameson and Cork Dry Gin.
This month, summonses were issued against Tesco and Dunnes for allegedly selling babyfood below cost. The case is to be heard in January
Foley acknowledged the drinks offer was different. “It’s not direct below-cost selling as there are two stages.” She said loyalty cards had earlier been of minor significance but recent discounts of 10% at Tesco and 15% at Dunnes put retailers “potentially in breach” of the below-cost selling ban.