Online shopping at Marks & Spencer is expected to be “fully on” within four weeks as it recovers from a cyber attack, the retailer’s boss has said.

Although M&S restarted online orders in June, half of its online operations – including click and collect – are still down, Stuart Machin told the retailer’s annual general meeting (AGM).

M&S will then focus on getting its Castle Donington distribution centre “back and running”, Mr Machin said.

The retailer hopes that by August “we will have the vast majority of this behind us”, he said.

The cyber attack in April locked up M&S systems, hitting sales for about six weeks, and the hackers also stole some customer data.

The attack, which disrupted M&S online shopping and left some shelves bare in stores, will hit this year’s profits by around £300m, the retailer has estimated.

This would only partly be covered by any insurance payout.

Mr Machin told shareholders at the AGM: “Currently, half of online is open but not areas like click and collect. Within the next four weeks we are hoping for the whole of online to be fully on.

“Then our focus will be getting the Donington site back and running.”

M&S had previously said services would continue to be disrupted in June and July.

There are some signs that the disruption helped some of the retailer’s rivals.

Supermarket chain Sainsbury’s said on Tuesday that it had seen “a little bit of benefit” from stock being down in M&S stores due to the attack.

“It stands to reason. If a particular store is lower on stock in the moment, a customer will go somewhere nearby,” said chief executive Simon Roberts.

Susannah Streeter, head of money and markets at Hargreaves Lansdown, said that although the retailer had strength, “there’s still a lot to get back online before the company can put the cyber attack behind it”.

There are early signs of “pent-up demand”, for its summer fashion styles, “with many of the popular products sold out online”.

She added that its strong set of annual results showed the retailer was “in a resilient position” before the attack, which “bodes well for M&S ahead”.