German Cybercrime watchdog the Federal Office for Information Security said Tuesday it had discovered a massive theft of email addresses. BSI said that the digital identities of 16 million online users had been stolen, compromising their email accounts, linked social media and other services.

The office has made available the https://www.sicherheitstest.bsi.de website to all internet users, where can enter their e-mail addresses to check whether they have been affected by the identity theft.

About half of the affected accounts had email addresses with Germany's domain-name ending .de.

Those affected were advised to check their computers for potential malware using anti-virus software, and change their passwords replacing them with more complicated combinations ofletters, numbers and symbols.