Tesco shoppers are being urged to check their bank statements after the supermarket chain admitted a "technical error" has resulted in customers being charged twice for their groceries.

The error has seen thousands of shoppers charged twice for in-store purchases over the past week, consumer website MoneySavingExpert has warned.

Tesco say it is working to reverse the double transactions promising to refund all affected customers within a day.

Customers are being told the money may not arrive back in their bank for a couple of days depending on how it is processed by their bank provider.

Not all stores have been affected by the glitch in the payment system and no online sales are affected, but the Times has been notified by Tesco shoppers in Borehamwood that they have been affected by this error.

Steve Nowottny, news and investigations editor at MoneySavingExpert.com, said: "This is clearly a major error which has led to many customers being double-charged. While we don’t have precise figures, the scale of complaints we’ve seen – from Tesco customers all over the UK – suggest the problem’s significant and widespread.

"If you’ve shopped in-store at Tesco recently and believe you may have been affected, check your account. Tesco says it’s automatically refunding customers within a day, but if you've been double-charged you should make sure the refund comes through.

"It may take several days for banks to process refunds, so you may unfortunately need to wait to get your money back."

Steve also said Tesco would be willing to consider refunds case by case if the error has led to other charges, for example if the payment has meant shoppers have gone into an unarranged overdraft.

He added: "If you’ve been left out of pocket, for example because you’ve unexpectedly gone into your overdraft and been charged bank fees, complain to Tesco.

"Given it’s mistakenly double-charged customers, it should be willing to put things right."

A Tesco spokesperson told MoneySavingExpert: "Due to a technical error some customer card payments have been authorised more than once.

"We’re sorry for any inconvenience this may have caused, and we want to reassure affected customers that they will only pay for their purchases once and any duplicate transactions will be reversed."

For more information and advice head over to MoneySavingExpert.com.