The largest known distributed-denial-of-service (DDoS) attack in the history of the internet is currently slowing down the Net worldwide.
The slowdown is because of a fight between a company attempting to stop the spread of spam emails, and a Dutch company that hosts the spammer's servers.
It was causing widespread congestion Wednesday evening to critical infrastructure around the world.
The squabble between Spamhaus, a spam-fighting group based in London and Geneva, and hosting service CyberBunker is causing a global slowdown of internet speeds and leading to frustration for those unable to access websites as quickly as normal or stream TV shows online, analysts said.
Up to five separate international police forces are investigating the incident.
It is the sheer scale of the attack which will be most worrying for those charged with protecting the underlying structure of the internet.
The attack is larger than anything ever seen before with the attackers flooding Spamhaus servers with up to 300 billion bits per second (300Gbps) of data.
Darren Anstee from Arbor Networks Solutions said attacks of 100Gbps are the largest recorded before now, and if it this attack is 300Gbps, it is "substantially larger" than anything ever seen before.
Steve Linford, chief executive for Spamhaus, told the BBC the scale of the attack was unprecedented.
"We've been under this cyber-attack for well over a week. The attack not only knocked Spamhaus' website and mail systems offline, such was the volume of traffic that it affected a much wider pool of internet users."
He added that if a similar attack was aimed at critical government infrastructure, then it would be instantly knocked offline.
"If you aimed this at Downing Street they would be down instantly."