Google’s web analytics tool can be used for free by any website, and according to research agency Xamit it is used by around 13% of German sites. But because web users are not given the chance to opt out of having their activity tracked, the federal data protection commissioner, together with regional officials in Berlin, Hamburg, Bavaria and Schleswig-Holstein, has warned that the use of the tool could be punishable by fines of up to €50,000.

Officials in different regions are taking different approaches to enforcement, with a spokeswoman for the Berlin data protection authority saying that resources would probably only allow for the use of Google Analytics to be monitored on an ad hoc basis – but that this could change without warning. In Schleswig-Holstein, websites can submit their processes for testing to find out if they are in compliance with the rules.

Die Zeit estimates that nearly two million sites in Germany use Google Analytics – more than twice the number who use all other similar tools.

Google has rejected claims that it could use the data it gathers to build comprehensive profiles of users’ behaviour, insisting that no such profiles are created. It argues that there is no need for an opt out because users can already use their browser settings to reject cookies, and says that it deletes all cookies after 18 months and anonymises IP addresses after nine months.

Federal and regional data protection officials are expected to come up with a set of requirements this week that must be fulfilled by website owners who implement analytics tools.