Tesco has been hit by hackers, leaving thousands of frustrated shoppers unable to buy groceries online at Britain’s biggest supermarket. The outage leaves its grocery website and app down for a second day, with people unable to book deliveries or amend existing orders. Tesco receives 1.3m online orders every week. A Tesco spokesperson said: “Since yesterday, we’ve been experiencing disruption to our online grocery website and app. An attempt was made to interfere with our systems, which has caused problems with the search function on the site. We’re working hard to fully restore all services and apologise for the inconvenience. “There is no reason to believe that this issue impacts customer data and we continue to take ongoing action to make sure all data stays safe.” Tesco was hacked previously in 2014, when it was forced to deactivate online customer accounts after more than 2,000 login details, including passwords, were posted online. A separate attack on Tesco’s banking arm resulted in the loss of £2.5m two years later. Cyber-attacks have become increasingly common and many companies and other organisations have been targeted globally. This summer, a cyber-attack on the Brazilian meat processor JBS, the largest in the world, forced it to temporarily stop production in the US, Australia and Canada. Shoppers voiced their frustration on social media. Some posted messages they had received from the supermarket telling them that because of the “current IT issue” Tesco was unable to access or change any orders at the moment. Sara Willman, a wholesale seller of flowers to florists in Wiltshire, tweeted that she had been told to send a direct message to cancel her order due, on Sunday, but later received a reply from Tesco saying that was not possible. “I understand you still have IT issues but much as I love gin I don’t need 2 bottles & some crisps this evening, when @asda saved the day with actual food this morning,” she said. Customers complained that there had been no update for 24 hours after Tesco had tweeted on Saturday: “We’re experiencing an issue with our website and app and are working hard to get things back up and running. We apologise for any inconvenience.” Several Tesco customers said they had placed incomplete orders to secure their delivery slots and were unable to add to them. A Tesco customer service member said via Twitter that if customers no longer wanted their order, the driver would take it back to the store for a refund. On Sunday morning, the company tweeted: “Our IT teams are doing their best and will have the website and app working as soon as possible. At the moment, we don’t have any updates or a timeframe as to when we can expect this to be. I am really sorry. TY – Cameron.” The rival supermarket Asda stepped in quickly on Saturday when it said on Twitter: “Hi there, hopefully we can help. We have slots available and some for the same day or tomorrow, if you go to our website or app it will allow you to place an order for items you need :).”