NEW YORK -- Facebook says it is testing out its own ad network that would deliver advertisements to mobile applications outside of its own.

The social networking company said in a blog post Wednesday that while it has run similar tests in the past, the current program is more like a mobile ad network. The company says it is working directly with a small number of advertisers and publishers rather than an outside ad-serving platform.

Menlo Park-based Facebook is not saying which advertisers or app developers it is working with. It says it will extend its ad-targeting capabilities to show app users more relevant ads, help developers make more money and provide Facebook advertisers with greater reach.

Mobile ads accounted for nearly half of Facebook's $1.8 billion advertising revenue in the third quarter.