File photo: a Tesco employee uses one of the supermarket's self-service checkouts Tesco

Almost one in four Brits admit to stealing items while using supermarket self-service tills, a new survey has said. The small thefts add up: with £3.2bn thought to have been lost in the practice - and the number is rising.

According to the survey, carried out by VoucherCodesPro.co.uk, the rate of Britons saying they have stolen at least one item while using the automated tills has doubled in the last four years. The most commons items being pinched are fruit, vegetables and dairy products, the research suggests.

One reason given by many participants however was technical difficulty with the machines themselves, with 62% of people saying the item they took would not scan - a third of people said they simply did not realise they had stolen anything until they had already arrived home.

A spokesperson for VoucherCodesPro.co.uk quoted in The Times, George Charles, said: "I'm sure most of those who now admit to stealing via self-service checkouts didn't initially set out to do so: they may have forgotten to scan something and quickly realised how easy it was to take items without scanning them. No doubt there's an element of risk, but when people start stealing it can be difficult to stop, until you get caught, particularly when money might be tight.

"Supermarkets need to increase the number of staff who monitor the self-scan checkouts, even though the point of these checkouts is to reduce the need for staff, as well as increase security." For those who admitted pilfering items while using the machines, the monthly average of stolen goods was around £23.

While the machines have taken the place of human cashiers across the country, staff are still required to check IDs for age-restricted items such as alcohol - but that might soon change. According to a report in the Telegraph, some supermarkets are looking to trial a facial recognition app that would serve as an identification method at the checkouts.