Supermarket giant Tesco will issue 600,000 new Clubcards to customers due to a security issue.
The company believe a collection of stolen data from another organisation have been utilised in order to try to gain access to up to 620,000 Clubcard accounts.
Those impacted by the matter were sent an email by Tesco to make them aware of the issue.
Additionally, Tesco has cancelled all affected vouchers.
Tesco maintains that no financial information was accessed and that their platform was not hacked and that their decision was taken as a precaution.
A Tesco statement read: “We are aware of some fraudulent activity around the redemption of a small proportion of our customers’ Clubcard vouchers.
"We have strict security measures in place and our priority is protecting our customers.
"Our internal systems picked this up quickly and we immediately took steps to protect our customers and restrict access to their accounts.
"At no point was any customer’s financial data accessed.
"We believe that someone has stolen password/username combinations from other website(s) and used them to try to access Tesco sites - where customers used the same username and password.
"We have asked customers affected to reset their passwords and are contacting customers whose Clubcard vouchers may have been affected to let them know that we will replace these vouchers and issue new Clubcards, as a precaution.
"We are sorry for any inconvenience this may cause.”
A number of customers impacted by the matter have had their accounts frozen by Tesco, as they await the matter being solved.
One customer tweeted: "How the freak does someone commit fraud on a @Tesco clubcard."
Tesco have asked people with concerns over the matter to contact their customer services department.