The Labour Party confirmed a cyber incident in which “a significant quantity” of party members’ data “rendered inaccessible on their systems, “suggesting a possible takeover by attackers.

The Labour Party also said the incident was related to information the party had received from its “members, registered and affiliated supporters and other individuals who have provided information.”

While news of the incident was relayed to the party by the third-party contracted to process membership data, the Labour Party confirmed that its own data systems were not affected and that it was working closely with authorities such as the National Crime Agency to solve the mystery behind the attack.

Speaking on the issue, a spokesman for the NCSC said: “We are aware of this issue and are working with the Labour Party to fully investigate and mitigate any potential impact. We would urge anyone who thinks they may have been the victim of a data breach to be especially vigilant against suspicious emails, phone calls, or text messages and to follow the steps set out in our data breaches guidance.”