Sainsbury's online store was knocked offline for several hours yesterday for the second time in a month, following a problem at network operator Cable and Wireless.

"The issues have arisen following a break-in at one of our network sites in Watford, in which some of our equipment was stolen," said a Cable and Wireless spokesperson.

According to The Telegraph, the thieves may have been looking for copper wire – which has a high scrap value due to rising copper prices.

Yesterday's outage is the second time in a month Sainsbury's site has been knocked offline. The service was unavailable in mid-June due to computer problems affecting the online store's processing systems.