Germany has told Google, Apple and providers of other online map services they have until 7 December to install voluntary guidelines on data protection - or face legislation to protect consumer privacy.
There has been strong public opposition over plans by Google to publish ground-level images of German cities on its street view service.
Der Spiegel news magazine reports 'several hundred thousand' people have already opted out of the service.
Interior Minister Thomas de Maiziere said that the proposal to establish a code by 7 December will enable users to obtain information on the gathering and intended user of data "in a user-friendly way".
Google is yet to launch street view in Germany, which has strict privacy laws.
It wants a mapping service of 20 German cities to be live by November, but has extended a deadline for users to opt out the mapping service until 15 October.
