Dutch authorities arrested three individuals last week accused of running one of the largest ever hacker botnets comprising over 100,000 zombie PCs.

The three men, aged 19, 22 and 27, were not named. Police confiscated computers, cash and a sports car during searches of the suspects' homes.

A botnet is a collection of hacked computers at the disposal of a hacker without the owner's knowledge. Botnets are commonly used to launch distributed denial of service (DDoS) attacks or to send spam.

With over 100,000 infected systems, the network is one of the largest ever detected, prosecutors claimed.

The suspects will be charged with computer hacking, destructing automated networks, and installing adware and spyware.

The trio used the W32.toxbot internet worm to recruit systems for their botnet army. The worm was first detected early this year and infected systems all over the world.

Antivirus software to detect and remove the software is available, but the suspects kept changing their malware to avoid detection.

The authorities are also investigating the group's involvement in a blackmail attempt on an unnamed enterprise in the US.

It is common practice among online crime gangs to extort the owners of websites, forcing them to pay to prevent a DDoS attack on their networks.

It is also suspected that the group was involved in crafting internet worms with keystroke logging software to gather login names to commit credit card fraud and identity theft.