Anyone who has shopped at the Co-op is being warned that they could be at risk of scams and identity fraud, according to a leading cybersecurity expert.

The Co-op supermarket has issued an apology after hackers accessed personal data including names and contact details of its shoppers this week, just days after M&S and Harrods were also struck by cyber incidents.

While Co-op stressed that the hackers didn’t get hold of bank details or passwords, it did lose personal data including names and addresses to the attackers, which has been reported to the National Crime Agency.

Now, Professor Alan Woodward of the Surrey Centre for Cyber Security at the University of Surrey has told The Telegraph how Co-op customers’ details could be sold on the ‘dark web’ to scammers.

He said: “Data like that gets sold on. So you might not suffer a loss immediately. But if someone’s got your name, address, telephone number, email address, they actually sell those kinds of details on to scammers.

“The scammers then use them for socially engineering you into anything from giving you their bank details to phishing attacks where you log in and give away your login credentials, that type of thing.”

A Co-op spokesperson said: “As a result of ongoing forensic investigations, we now know that the hackers were able to access and extract data from one of our systems.

"The accessed data included information relating to a significant number of our current and past members.

“This data includes Co-op Group members’ personal data such as names and contact details, and did not include members’ passwords, bank or credit card details, transactions or information relating to any members’ or customers’ products or services with the Co-op Group.

“We have implemented measures to ensure that we prevent unauthorised access to our systems whilst minimising disruption for our members, customers, colleagues and partners.

“We appreciate that our members have placed their trust in our Co-op when providing information to us. Protecting the security of our members’ and customers’ data is a priority, and we are very sorry that this situation has arisen.”

A National Crime Agency spokesperson said: “We are aware of the recent cyber incidents affecting the retail sector and are working closely with our law enforcement partners to investigate.

“We are considering the incidents individually, however, we are mindful they may be linked and therefore this will remain under review.”