Millions of German internet users are affected by hackers, German Federal Office for Information Security (BSI) announced on Tuesday. Unknown perpetrators have stolen the netizens passwords and usernames for websites, according to the BSI, a total of 16 million accounts containing passwords and email addresses had been compromised. The BSI said that the lists of data that usually contains an email address and a password were handed over by the researchers and prosecutors to the BSI. The authority has set up a website, where the users can check on whether they are affected or not. Internet users can enter their e-mail address, which will be compared with the data. If a match occurs, the users will get a message to the indicated email address. "When the match happens, it means that your computer is probably infected with a malware," said Tim Griese by BSI. More than half of the email addresses ended with .de and belong therefore probably to the Internet users in Germany, Griese said. Based on the analysis, the access data were recognized on the botnets, which are networks of hijacked computers that have been infected with malware without the knowledge of users. The lists of data may indicate hijacked e-mail accounts, but the combination of email address and password is often used to log in to other services as well, such as online networks or shopping websites. Therefore, the BSI recommended that those people concerned should digitally clean their computer and modify access for their online profiles.