Tesco’s US business could be dealt a severe blow as a proposed ban on the sale of alcohol from self-service checkouts in California moves one step closer to becoming law.

More than 70% of Tesco’s 175 Fresh & Easy stores are in California and all rely solely on self-checkouts, giving it a huge cost advantage. However a union-backed bill which aims to tackle underage drinking has passed its first hurdle, according to The Times.

The California State Assembly has passed the measure but to become law, it must win the approval of the State’s Senate and a Senate committee, before coming in front of the Governor. The bill has been dubbed the ‘Fresh & Easy Bill’ in California as Tesco is the only retailer which operates unmanned checkouts.

MF Global retail analyst Mike Dennis said the passing of the bill would mark “the beginning of the end” for the supermarket’s US venture, which he says is already struggling.

A Tesco spokesman told The Times: “We are a responsible retailer and our systems restrict the sale of alcohol to underage customers. Sales of alcohol cannot be completed without the intervention from our well-trained staff.”