"We are adding another factor to News Feed ranking so that we will now predict how long you spend looking at an article in the Facebook mobile browser or an Instant Article after you have clicked through from News Feed," Facebook said in a press release.

"We will not be counting loading time towards this — we will be taking into account time spent reading and watching once the content has fully loaded. We will also be looking at the time spent within a threshold so as not to accidentally treat longer articles preferentially."

The update has started rolling out, with the company saying that the process will take a few weeks to complete.