Privacy watchdogs have strongly criticised Google's new Latitude software, which pinpoints the location of mobile phone users anywhere in the world.
Touted as a means for friends and family to stay in touch, Latitude could easily be abused by as a way of spying on people and keeping track of their movements.
Latitude is available in 27 countries and will work with most mobile phones, according to Google.
The internet company has defended the move saying users will have to sign up for the service and can decide what information to allow contacts to see.
Only the most recent location is given if that is what the user has allowed, and none of the information is stored to create virtual trails, said Google.
The UK Information Commissioner's Office, said users should be informed about how their information will be used, and the ICO will be monitoring Latitude closely.
Authorities in Italy this week began prosecuting Google employees for privacy breaches on charges of defamation and failure to exercise control over personal data.
The charges follow a two-year investigation by Italian authorities into a three-minute video posted to Google's Italian website in which four teenagers make fun of a disabled classmate.