Co-op customers should see stocks on shelves start to return to more normal levels this weekend, the company said, after it announced it was switching its online ordering system for suppliers back on after a cyber-attack.

The hack resulted in payment problems, widespread shortages of goods in shops, and compromised customer and staff data.

The hackers, who use the name DragonForce, also claimed to be responsible for a similar attack on Marks and Spencer (M&S) and an attempted hack of Harrods earlier this month.

Co-op said it was bringing its systems “gradually back online in a safe and controlled manner.”

Earlier this month, cyber criminals infiltrated the Co-op’s IT networks apparently trying to extort money from the grocery chain.

The company moved to limit the impact of the attack by shutting down some IT systems, including parts of its supply chain and logistics operations, resulting in disruption to deliveries.

Shoppers have shared images of empty shelves and fridges.

But Co-op says this should improve from the weekend in-store and online, as it works with its suppliers to restock.

It says all payments systems, including contactless payments, are back up and running.

In a statement, the company thanked “colleagues, members, partners and suppliers for their support so far.”

In a message sent to its suppliers earlier this week, and first reported by The Grocer, the Co-op asked for patience as it gets its systems back up and running.

It warned of likely increased “volatility” in order volumes.

The cyber criminals claim to have the private information of 20 million people who signed up to Co-op’s membership scheme, but the firm would not confirm that number.

M&S admitted on Tuesday that some customer data had been stolen in the hack of its systems.