In raids throughout Germany and Austria, police closed down a web gang which stole private credit-card data and used viruses to create a network of 100,000 robot computers, Germany’s Federal Crime Office said Wednesday.

In Germany, three persons were detained during the Tuesday raids on 46 homes. One was held in Austria. Many computers were seized.

The offenders, aged 15 to 26, knew one another via an internet forum devoted to hacking and hid behind nicknames. Police took a year to infiltrate the forum and gradually uncover their true identities.

The Austria administrator of the forum set up the so-called bot net, in which 100,000 computers, unknown to their owners, were infected with virus software and were doing his bidding, providing him with both massive networked computing power and secrets.

The forum named itself the ‘Elite Crew’ and was devoted to swapping ideas on how to outwit credit-card security features, hack into other people’s computers and spread viruses, according to the Federal Crime Office.