Google has restricted social networking site Facebook from grabbing information about its users' contacts in Gmail, the search engine giant's email service, a media report said.
Until now, new Facebook users could find out whether their contacts on Gmail also had Facebook accounts, simply by typing in their Gmail user name and password as part of the Facebook signup process, the Wall Street Journal reported on Friday.
Google's policy helped Facebook grow because it helped new users instantly create a network of friends on the site. Unlike Google, Facebook doesn't allow its users to export their contacts data to other websites.
With Google becoming more and more interested in social networking and internally developing a competitor to Facebook, people familiar with the matter have said Google has called on Facebook to provide more access to user information.
Google chief executive Eric Schmidt recently said Google hoped to get access to Facebook users' contact lists so that people can expand their social network on Google, though he added there were alternatives if Facebook didn't comply.
But Facebook did not respond, leading Google to change its position this week.
Google no longer allows Facebook users to automatically export their Google contacts data as long Facebook continues to block Google from gaining the same access to Facebook contacts data with users' permission, the report said.
A Google spokesman said in a statement that its policy change reflects "the fact that users often aren't aware that once they have imported their contacts into sites like Facebook they are effectively trapped".
"We hope that reciprocity will be an important step towards creating a world of true data liberation and that this move will encourage other websites to allow users to automate the export of their contacts as well," the spokesman said.
Google users can always export their contacts from Gmail and other Google services to their computers in a machine-readable format, the spokesman said. Once they have done that, they can then import those contacts to Facebook.
A Facebook spokesman declined to comment.
Google's move comes six years after the launch of Facebook that now has more than 500 million users, many of whom previously exported their Gmail contact lists to Facebook.