Tesco’s delivery service has crashed after being hit by an IT system failure, resulting in customers’ grocery drop-offs being cancelled.

Customers took to Twitter in droves to complain as their deliveries were cancelled within minutes of their scheduled time slots.

Tesco said that the problem started this morning and has affected less than 10% of orders.

Tesco is unclear on exactly what caused its systems to break down but said that the problem was within its picking department.

A Tesco spokesperson said: “We’re currently experiencing an IT issue which is affecting some grocery home shopping orders. We’re working hard to fix this problem and apologise to customers for any inconvenience this may cause.”

The failure comes as Tesco begins to gain traction on its turnaround plan under boss Dave Lewis.

The grocer has outperformed its big four rivals in recent months, gaining a 27% market share in the 12 weeks to May 21. The second biggest market share, held by Sainsbury’s, came in at just 15%.