HANOVER, May 8: German police have arrested an 18-year-old man suspected of creating the "Sasser" computer worm, believed to be one of the Internet's most costly outbreaks of sabotage.

Spokesman Frank Federau for Lower Saxony police said the man was arrested on Friday after software giant Microsoft gave police a tip-off on the source of the destructive worm.

Microsoft itself had previously received anonymous tip-offs on the worm's creators, Mr Federau said.

"We are absolutely certain that this really is the creator of the Internet worm because Microsoft experts were involved in the inquiry and confirmed our suspicions and because the suspect admitted to it," he told Reuters in an interview.

Microsoft, the US Federal Bureau of Investigation (FBI) and German police had all worked together to find the suspect, Mr Federau said.

He said the man, who he described as a highly intelligent "computer freak" living with his parents, was arrested on Friday near the central German town of Rotenburg but was later released.

Police said it appeared the arrested man acted alone and there were no other suspects. The arrested man is suspected of "computer sabotage", a charge carrying up to five years imprisonment in Germany.

Since appearing a week ago, Sasser has wreaked havoc on personal computers running on the ubiquitous Microsoft Windows 2000, NT and XP operating systems, but is expected to slow down as computer users download anti-virus patches.

The computing underground responsible for hatching worms and viruses has proved a difficult ring to crack for law enforcement.-Reuters