Supermarket giant Coles saw entire stores knocked offline due to an IT glitch over the weekend.

Signs posted on stores around the country claimed an “IT issue”, “network error” or “system issues” that were “beyond their control” meant transactions could not be processed.

Stores were knocked offline for just over an hour on Sunday. Social media users posted photos of long lines waiting for Coles to reopen.

A Coles spokesperson said on Sunday afternoon that “all Coles supermarkets are [now] open and trading”.

“Earlier this morning we had some minor IT problems in some of our supermarkets which were out of our team members’ control,” the spokesperson said.

“We apologise for any inconvenience our customers experienced earlier this morning.”

The company has given no detail about the cause of the outage, but there was some indication that the problems were due to outsourced IT systems.