Police are investigating claims that dozens of Tesco customer Clubcard accounts may have fallen victim to an online fraud. Complaints made by customers include reports that users logging into their Clubcard online accounts have found hundreds of pounds worth of vouchers missing.
Others say they have been unable to log on.
It is thought the number of complaints received by Tesco is less than 100, while a handful of customers have been reimbursed.
In a statement, Tesco said: "We have launched a thorough investigation into a small number of incidents and referred the matter to the police. In the meantime, we'd like to ask any customers who believe they're affected to contact us directly so that we can make sure their accounts are up to date."