Asda this week launched a major promotion of alcohol offering shoppers three boxes of selected beer, cider and RTDs for just £18.

The deal has hit shelves less than three months after the retailer pledged to stop selling alcohol below cost in what it described as "a small, but important first step towards creating a new way of selling alcohol in the UK".

In July, chief executive Andy Clarke wrote to Theresa May, the home secretary, and pledged that the supermarket would not sell alcohol below the cost of duty plus VAT. "At Asda we recognise more needs to be done to tackle alcohol misuse," he wrote.

While this week's deal was not below its definition of cost, it leaves little for the cost of production. The deal includes 15 x 300ml bottles of Budweiser, for example, with duty and VAT totalling £13.74. This leaves just £1.42 per crate for production and sales costs.

An Asda spokesman declined to comment on suggestions the deal was irresponsible. "We remain committed to not selling alcohol below the cost of duty plus VAT," he said.