SAN FRANCISCO: Facebook, the social network, has announced a new trial programme that will see it insert ads in users' News Feeds based on their online browsing interests.

The move builds on the launch of Facebook Exchange (FBX) last year, which enabled businesses to run standard ads on the right-hand sidebar of Facebook pages on desktop computers.

"Allowing advertisers to reach people in news feed is important because people spend more time in News Feed than any other part of Facebook," the company stated in a blogpost.

"We also believe that ads delivered through FBX will create more relevant ads for people," it added.

Advertisers are now able to run "Page post link ads" which will point back to specific landing pages, a move that could help direct-response advertisers drive conversions.

But observers also expressed reservations about this approach. Richard Greenfield, an analyst at BTIG Research, told the Financial Times that a lack of social context for the appearance of such ads risked making the social network feel "spammy".

Rebecca Lieb, an analyst at Altimeter Group, used the word "creepy" to describe the effect of adverts seeming to follow people around the web, especially when they appear in a personal news feed.

And while these ads are currently restricted to the desktop version of Facebook, there is an expectation that they will eventually appear on mobile devices as well.

The scope for monetisation is clear from the figures that Facebook has released: in January, chief operating officer Sheryl Sandberg said FBX was serving around 1bn impressions from 1,300 advertisers every day.

Data sourced from Facebook, Financial Times, Advertising Age; additional content by Warc staff