A Dutchman accused of launching an unprecedented cyberattack that reportedly "almost broke the internet" is to go on trial Tuesday on charges of masterminding the 2013 incident that slowed down web traffic world-wide.

But Sven Olaf Kamphuis, 39, denounced the case against him, and told the AD daily newspaper in a Skype interview that he would not appear at the court in the southern Dutch city of Dordrecht. He will be represented by his lawyers.

He is accused of being behind a massive so-called distributed denial of service (DDoS) attack in March 2013 on Geneva and London-based volunteer group Spamhaus, court spokeswoman Lily Derksen told AFP.

Spamhaus publishes spam blacklists used by networks to filter out unwanted email. And it blamed Dutch web-hosting service Cyberbunker for the attack, one of the largest in the history of the internet at the time.

At the time, Kamphuis was said to be a spokesman for Cyberbunker.

"The cyberattack and its subsequent domino effect was so big that the world came within a hair's breadth of being without the internet for a week," the popular daily tabloid Algemeen Dagblad said.

Arrested in Spain, Kamphuis was eventually extradited to The Netherlands, where he was remanded for two months in May 2013.

Kamphuis -- who refers to himself as the "minister of telecommunications of the Cyberbunker republic" -- told the AD newspaper that the charges were "absurd."

He added he is counter-suing the Dutch state for 102 million euros ($111 million) in damages.

Kamphuis' lawyer Marcel van Gessel told the paper his client was "out of the country" and it is believed he was either living in Barcelona or in Berlin.

So-called distributed DDoS attacks essentially bombard sites with traffic from various sources in order to disrupt or seize servers.

The attack was described as the most powerful ever seen and slowed web traffic.

The attacks began, according to Spamhaus, after it placed Cyberbunker, a web hosting firm that "offers anonymous hosting of anything except child porn and anything related to terrorism", on its blacklist.

Cyberbunker said it had been unfairly labelled as a haven for cybercrime and spam.

Experts said the attacks flooded Spamhaus servers with 300 billion bits per second (300 gigabytes) of data. Prior DDoS attacks had been measured at 50 gigabytes per second.