The National Crime Agency has arrested four people in connection with recent cyber-attacks on Marks & Spencer (M&S), The Co-operative, and Harrods.

Following an investigation by the law enforcement agency, two males aged 19, another aged 17, and a 20-year-old female were apprehended in the West Midlands and London on Thursday.

They were arrested on suspicion of Computer Misuse Act offences, blackmail, money laundering and participating in the activities of an organised crime group.

All four were arrested at their home addresses where their electronic devices were seized for digital forensic analysis.

They are currently in custody for questioning by officers from the NCA's National Cyber Crime Unit.

"Since these attacks took place, specialist NCA cybercrime investigators have been working at pace and the investigation remains one of the Agency's highest priorities," said deputy director Paul Foster, head of the NCA's National Cyber Crime Unit.

He went on to say that the arrests mark a "significant step" in its investigation, adding that the organisation's work will continue alongside partners in the UK and overseas to "ensure those responsible are identified and brought to justice."

A Co-op spokesperson commented: “Hacking is not a victimless crime. Throughout this period, we have engaged fully with the NCA, and relevant authorities and are pleased on behalf of our members to see this had led to these arrests today.”

Retail Systems has approached M&S and Harrods for comment.

The April attack on M&S forced the group to close its online store for nearly seven weeks and led to empty shelves at shops during May as automated stock systems were shut down. The incident has cost the company an estimated £300 million in lost profits this year.

Last week, the company said it would be over the worst of the attack by August.

The cyber attack, which has been linked to hacking group Scattered Spider, disrupted contactless payments and click-and-collect services. It also led to a data breach involving staff information, though M&S said no sensitive details such as passwords or home addresses were accessed.

In a similar attack, Co-op had to close down several business services for staff operating stores and its legal services division.

The company's stock monitoring system was also impacting, leading to empty shelves at some of its stores.

The Cyber Monitoring Centre (CMC) recently classified the cyber attacks on M&S the Co-op as a Category 2 systemic event in its first live public assessment of the financial impact on the UK of a cyber incident.

Harrods also faced an attack which forced it to restrict access to its websites.

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