With self-service-only tills, a new Tesco Express store, in Northampton, has been hailed as "the future" by the retailer.

It is the first convenience store in the country with no cashiers or traditional checkouts and is being used by Tesco as an experiment to gauge customers' response.

"People are naturally wary of new technology, but once someone has used an 'assisted shopping checkout' they are very loyal to them. They are simple to use and fast," the spokesman added.

Tesco insisted the move was not a cost-saving exercise and the same number of staff would be on hand to assist if there were problems. The move, it said, enabled staff to move around the store and help shoppers. If any customers did not want to scan their own shopping, a member of staff would do it for them and talk them through the payment process. The store also has a self-service tobacco counter with a computerised display, also thought to be the first in the country.

Tesco's US business Fresh & Easy already has some stores with 100% self-service tills, but the spokesman said Tesco currently had no plans to take the concept to any other UK stores.

Shopworkers union Usdaw said it would keep an eye on any changes to staffing levels. "Self-checkouts are something we monitor very closely as they could have an impact on jobs," said John Hannett, Usdaw general secretary. "I think people still like being served by a human."

Other supermarkets have expanded their use of self-service tills over the past year, and some fuel-only forecourt operations are now self-service only, but no other retailer in the UK has plans to completely remove traditional tills from its stores.

Asda said 99% of its stores had self-service tills and this would rise to 100% of stores by next spring, but it had no plans to follow Tesco's lead. "It's about offering choice," said a spokeswoman.

Sainsbury's is adding self-scan checkouts to 47 stores and said it expected between 25% and 40% of transactions to go through the new tills.

Morrisons is also pressing ahead with the technology, adding the tills to 160 of its stores.