The M&S website is down - hours after the retailer revealed it's facing a £300m hit to profits following last month's ransomware attack.
A holding page told customers that they are currently unable to browse the site, adding: "We're making some updates and will be back soon."
Online purchases have been suspended since the incident on 22 April, and it may be a couple of weeks before services are partially restored.
Sky News understands that the maintenance is routine.
M&S recently warned that disruption to its operations could last into July, but chief executive Stuart Machin says the retailer is "on the road to recovery".
It is widely believed the retailer fell victim to Scattered Spider, a hacking group that has also been linked to similar attacks targeting The Co-op and Harrods.
Last week, M&S also admitted personal data belonging to some of its customers has been stolen - but the company stressed this didn't include "usable payment or card details".
Passwords were also not affected, but there are reports that contact details such as names, addresses and phone numbers was taken.
The company's valuation has plunged by more than £1bn as the fallout deepens.
"This incident is a bump in the road, and we will come out of this in better shape, and continue our plan to reshape M&S for customers, colleagues and shareholders," Mr Machin told analysts on Wednesday.
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