Some 330 SPAR stores in the north of England are in the midst of serious operational problems after being hit by a cyber attack at the weekend that closed many of their stores and forced many to revert to cash-only payments.

SPAR is a global supermarket franchise with 13,320 stores in 48 nations, but the latest security incident only affected its stores in the north of England.

Lawrence Hunt & Co Ltd., which operates about 25 offices in Lancashire, UK, said the “total IT outage” had a serious impact on cash registers, credit card payment systems and the disabling of email access.

SPAR Ribchester did not provide an estimate for the recovery of the systems.

While the incident shows signs of a clear ransomware attack, the official nature of the cyberattack has not yet been officially identified.

The UK’s National Cyber Security Centre has issued a statement informing consumers that the authority is aware of the situation and is currently assessing the incident.