Social networking giant Facebook plans to engage in a new type of mobile advertising based on the apps used by consumers, The Wall Street Journal reported Saturday on its website.

The social network, which has 900 million users, would use its Facebook Connect feature -- which lets millions log into applications using their Facebook ID and password -- to track consumers' apps, and tailor ads accordingly, it said.

Facebook -- which is based in Menlo Park, California -- may also attempt to track how people use the apps, but a final decision has not been made, the newspaper said, quoting unnamed sources familiar with the company's plans.

The plan is likely to stoke privacy fears, as the initiative would go further than current mobile-ad networks, which track ads viewed by consumers on their mobile phone's web browser, the report said.

One of the biggest challenges Facebook must confront is its difficulties in generating revenues from smartphones, with more and more users accessing the social networks from mobile devices.

That factor led analysts to downgrade their forecasts for the group before its stock market debut in May, which ended up being less than a success.

At that time, Facebook shares were offered at $38. Shares closed Friday at $31.73.