A police spokesman said the man was arrested on Friday. No other details were available.
German newsweekly Der Spiegel reported that the CIA and FBI also were involved in the hunt for the worm's creator, whom it identified as Sven J.
Sasser, a tenacious computer worm, is expected to infect millions of machines before it runs its course.
Since appearing at the weekend, it 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.
Home users, corporations, and government agencies throughout Europe, North America and Asia have been hit. Once infected, the vulnerable PC reboots without warning as the compact programme hunts for more machines to infiltrate.
Sasser could mutate by combining with the two-month-old Netsky worm, making it a launching pad for further web attacks that would put it on par with Blaster, the destructive worm that appeared last year and used infected computers to attack Microsoft Corporation's website.
Microsoft this week declined to say whether it planned to offer a reward for information leading to the arrest of Sasser's author, such as the $250,000 reward it offered for the Blaster creator.