An investigation by The Grocer has uncovered a host of stores suspected of selling duty-avoided alcohol trading under the Select & Save, Premier, Nisa and Spar fascias.

Following tip-offs, The Grocer commissioned marketing agency Field Agent to visit a number of stores across the country and photograph suspicious-looking deals.

Deals spotted included single cans of super-strength lager for £1.19 - 13p below duty and VAT and cheaper than the multiples, which sell four cans of Special Brew for £7.05. One retailer was also selling Dannoff vodka for 46p below duty and VAT.

The Grocer has passed details of the retailers, who had to be either buying the goods from an illegal supplier or selling them at a loss, to symbol group operators.

A spokeswoman for Booker said: “With the wide availability of duty-avoided stock, we are not surprised that with 2,700 members, a few customers will unknowingly take a risk.”

Select & Save MD Kam Sanghera agreed it was difficult to identify suspected stores. “Unfortunately, we can’t monitor our members, and I’m sure this is an issue within most symbol groups,” he said.

However, fraud experts warned that franchisors who turned a blind eye to retailers they suspected of selling illicit alcohol could be prosecuted under the Proceeds of Crime Act.

“Prosecutors might make an argument that, by selling services that allow it to continue trading, the franchisor is facilitating what the retailer is doing,” said Siân Darlington, a senior associate at solicitors Pannone. “They would only have to prove that the franchisor had a suspicion that the retailer was up to no good, not that they knew it.”

A Spar spokeswoman said it would “tackle the issue head-on with any retailer who compromises Spar’s position.”

Nisa symbol director John Heagney threatened to remove membership from those involved in duty fraud. “Action will be taken to any member found to have been involved in such activity,” he said.