Marks & Spencer said on Tuesday some stores have been left short of some food items as it continues to grapple with a "cyber incident".
M&S stopped taking clothing and home orders through its website and app last Friday following problems with contactless pay and click and collect services over the Easter holiday weekend.
An M&S spokesperson said that as part of its "proactive management of the incident" it had taken some its systems temporarily offline.
"As a result, we currently have pockets of limited availability in some stores. We are working hard to get availability back to normal across the estate," the spokesperson added.
While M&S has not disclosed the nature of the cyber incident, cyber security experts have said the fact that M&S took systems offline suggested it was likely a ransomware-related event.
The spokesperson declined to say when online orders are expected to resume.
The 141-year old M&S, which has about 1,000 stores across Britain, makes around one third of its clothing and home sales online.
Analysts have said a short term profit hit is inevitable.
Shares in M&S closed Tuesday up nearly 1 per cent but are down nearly 6 per cent over the last week.
M&S's food business had been trading well prior to the cyber incident.
Market researcher Kantar said on Tuesday that spending on groceries at M&S grew by 14.4 per cent in the 12 weeks to April 20 year-on-year.
(Reuters)