Fake news may have already influenced politics in the US, but it's going to get a lot worse, warns an AI consultant to the CIA.

Sean Gourley, founder and CEO of Primer, a company that uses software to mine data sources and automatically generate reports for the CIA and other clients, told a conference in San Francisco that the next generation of fake news would be far more sophisticated thanks to AI.

"The automation of the generation of fake news is going to make it very effective," Gourley told the audience at EmTech Digital, organized by MIT Technology Review.

The warning should cause concern at Facebook. The social network has been embroiled in a scandal after failing to prevent fake news, some of it created by Russian operatives, from reaching millions of people in the months before the 2016 presidential election. More recently the company been hit by the revelation that it let Cambridge Analytica, a company tied to the Trump presidential campaign, mine users' personal data.