Germany's Federal Office for Information Security, or BSI, on Tuesday issued an alert to Internet users regarding the possible theft of 16 million identities and email access passwords.

BSI activated an Internet link so that users can verify if they are among those affected by the possible huge data theft and where they must provide the e-mail address they want to check.

If a person is among those affected, he or she will receive an e-mail from BSI with a series of instructions to follow to repair the damage.

Especially vulnerable are accounts that use the same passwords for different e-mail services and social networks, BSI said.

The link was blocked shortly after being activated, having been inundated by an overload of hits after the online editions of various media published information about the data theft including the Twitter account of government spokesman Steffen Seibert.

The possible theft was detected by BSI experts who advised members of the public to immediately change their passwords on their online accounts if they suspect they may be among those affected.