Google has begun reducing Facebook ‘s app on its phones. An update for its latest mobile OS will remove users’ Facebook contacts from the phone’s address book.

The update applies to the Gingerbread version of Google’s Android mobile OS. The platform is currently only available for the Nexus S and Nexus One handsets, being manufactured for Google.

If makers of other Android-based handsets start using the same version of Gingerbread as the Nexus phones, more users would find Facebook contacts removed from their address book.

Google has cited its data-sharing rules for the move.

Originally, Facebook’s Android app let users to have Facebook contacts in their phone’s address book. But the data was controlled by Facebook and could not be exported from the handset. Facebook does not offer a contacts API and this was not acceptable to Google.

Google said that since Facebook contacts cannot be exported from the device, the appearance of integration created a false sense of data portability.

In November, Google disallowed Facebook to Gmail’s contacts API saying it would not restore the connection until Facebook introduced a similar API.