"We are pausing our mobile ads test off of Facebook," a company spokesman said in an email response to an AFP inquiry.

"While the results we have seen and the feedback from partners have been positive, our focus is on scaling ads in mobile news feed before ads off of Facebook."

The test of placing ads in Facebook-linked apps will be halted by the end of the year as the California-based firm makes a priority of developing ways to profit from "news feeds" of posts shared between friends at the social network.

Facebook shares were down slightly on the news, slipping less than a percent to $27.60 in late afternoon trading on the Nasdaq exchange.

Facebook stock rallied in October after the company reported quarterly earnings that showed gains in tapping the mobile advertising market.

During an earnings call with analysts, founder and chief executive Mark Zuckerberg said the company was "just getting started with our mobile product development and monetization.

Facebook went public in May with a resounding flop, its $38 initial public offering price immediately plunging to eventually less than half that.

That angered many investors who had built hopes that the company's huge popularity would result in huge gains in the share price.

Analysts have questioned the company's ability to earn money from smartphones, where Facebook is finding its users more often now.