Pirates launched cyber attacks on the opposition Labor Party for the second time in two days, flooding its web services with heavy and harmful traffic designed to shut down the Internet just weeks before national elections, sources told Reuters.

The party said earlier on Tuesday that it was "subjected to sophisticated and large-scale cyberattacks on digital platforms," ​​but the attack was successfully repulsed and no data was compromised.

But a few hours later, the campaign site and other online services came under a second digital attack, according to two people familiar with the matter.

The sources said it was not clear if the second attack was launched by the pirates themselves who launched the first attack or not, but there is currently nothing linking the two incidents with a foreign country.

Asked about the second attack, a Labor spokesman said: "We have ongoing security operations to protect our platforms, so users may face some problems. We are dealing with this quickly and efficiently."

Britain's security services have warned that Russia and other countries could use cyber attacks or political messages on social media to try to disrupt the December 12 election. Moscow has repeatedly denied Western allegations of interference.

The British National Center for Cybersecurity, part of the electronic intelligence agency GCHQ, said the first attack was distributed for denial of service, or DDoS, a technique used by hackers. In stopping websites by flooding traffic on the site with fake requests so that the site is unable to meet all of them stop working.

"DDoS attacks are a common form of attack used by a very wide range of attackers," said a spokesman for the National Cyber ​​Security Center.

The nature of such attacks often made it difficult to establish responsibility for attacks, he added.

Labor leader Jeremy Corbin sees cyber attack on political party in elections as suspicious and something very worrying (Getty Images)
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Labor leader Jeremy Corbin said the first attack was very serious, but was successfully repulsed by the party's defense systems at the start of the attack on Monday.

"But if this is a sign of things that will come in this election, I feel very nervous about it all because the cyber attack on a political party in the election is suspicious and very disturbing."

A Labor spokesman said that although Monday's attack slowed some campaign activities, it was restored on Tuesday.

Britain is due to hold a parliamentary election on December 12 called by Prime Minister Boris Johnson in a bid to end Britain's exit from the European Union for more than three years since the country voted to leave the bloc.

A report by parliament's Intelligence and Security Committee investigated Russian activity in British politics and included accusations of espionage and interference in opinion polls, including the 2016 Brexit referendum and the 2017 national elections, but the government refused to publish it before the end of the next election.