M&S customers have been encouraged to take immediate action as the on-going cyber attacks continues to affect store services.

At the time of writing, shoppers are still unable to place orders online and staff cannot check if they have something in stock for customers.

The shop chain has also said that some customer details were taken in the attack, including some personal details such as email addresses and online order history.

Ross Brewer, vice president and managing director for EMEA at data management group , urged people to take action. He said: "If you suspect your credentials were compromised, change your passwords immediately.

"As a crucial first step, everyone, today, should comb through their accounts, resetting any passwords that are the same as the one that may have been compromised.

"Otherwise cybercriminals can potentially also access other accounts with the same password, such as utilities and banking, to cause more damage."

Ashley Bailey, founder of AI online shopping tool , also called on shoppers to make it a priority to change their passwords. He said: "Change the passwords from any email accounts immediately."

He also shared some tips to avoid being taken in by a fake email purportedly from M&S, noting: "Keep an eye out of phishing emails which are trying to act as a retailer.

"If you receive an email and you're unsure if it's real, click on the email domain at the top of the email and check to see if they match the retailer's website domain.

"This is the easiest way to spot a phishing email. If you're unsure, don't click and get some advice and never hand over your financial details."

Mohbeen Qureshi, tech expert at marketing group , encouraged shoppers to be "flexible and cautious" to avoid being impacted by a major cyber incident such as this.

He shared five practical tips to minimise your risk:

• Keep a short list of go-to alternatives for groceries, clothing, and essentials
• Use different payment methods so you're not stuck with store credit or gift cards that suddenly don't work
• Only trust updates that come from M&S's official channels
• Watch for fake promotions or phishing emails pretending to be from the brand
• Push non-urgent purchases to a later date.

Asked how long it could take for M&S services to return to normal, Mr Qureshi said: "Restoration usually happens in phases.

"First they secure the breach, then they test internal systems, then bring customer services back online. If the damage was major, this could stretch into July or beyond. Patience is part of the process."