Facebook Inc., operator of the world's largest social network, is opening its mobile messaging application in a bid to court new users.

A new feature will enable Android-based smartphone users to send texts, photos and other content to each other starting Tuesday in select countries, Facebook said in an e-mailed statement. While the Messenger app required all users to be Facebook members before, the service will now only need a phone number.

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Facebook is building out mobile features as people increasingly turn to wireless devices for their communication and computing needs. More than half of the social network's 1 billion active users already access the service on smartphones or tablets.

"You can create a Messenger account with just your name and phone number, and start messaging your mobile contacts," Menlo Park, Calif.-based Facebook said in the statement. "We're doing this because we're serious about messaging and realize that limiting the reach to just those on Facebook limits the ability for people to reach anyone in their address book."

The upgraded app, running on Google Inc.'s Android mobile software platform, will initially be available in Australia, India, Indonesia, South Africa and Venezuela. Facebook said it plans to expand it to other countries in the future. The Messenger application will eventually become available on Apple Inc.'s iPhone, the company said.