Political advertising that is only seen by its intended recipients is a greater cause for concern than “fake news” in the spread of misinformation, according to the director for a leading fact-checking charity in the UK.

So-called “dark ads” have emerged as a method of advertising that utilises data obtained by the likes of Facebook and Google to customise political campaigns.

They can be served directly to users of Facebook and via Google’s widely used double-click  technology which serves ads to millions of websites.