“We have experienced a sophisticated and large-scale cyberattack on Labour digital platforms,” Labour said in a statement. “We took swift action and these attempts failed due to our robust security systems.
The party was confident data breach occurred, it said.
Britain’s security agencies have warned that Russia and other countries could use cyberattacks or political messages on social media to attempt to disrupt the Dec. 12 election.
Moscow has repeatedly denied Western allegations of election interference and a person with knowledge of the matter said an initial investigation had found nothing to link the Labour Party attack to a foreign state.
Britain’s National Cyber Security Centre, part of the GCHQ signals intelligence agency, said the attack was a distributed denial-of-service (DDoS) attack - a technique used by hackers to take down websites by overwhelming them with malicious traffic.
“DDoS attacks are a common form of attack used by a very wide range of attackers. Mitigation techniques are available and worked in this case,” a NCSC spokesman said.
The nature of such attacks often made it difficult to attribute responsibility to any particular group, he said.