Facebook suppresses US conservative political news when compiling trending articles on the site, former workers have alleged.

The social network has implied that the trending section that appears along the right hand side of Facebook's website is chosen by crunching data on a story's popularity and timeliness. However, a former contractor who worked on this team has said the stories are often filtered by human news curators, similar to the homepage of a news website.

The ex-journalist revealed that they would regularly exclude US conservative topics for the section even if they were trending on the social network.

"I believe it had a chilling effect on conservative news," the curator, who identified as politically conservative, told tech site Gizmodo.