With Sweden going to the polls on 9 September, the study shows that Swedish social media users have shared two links to professional news content for every one link to junk news, with junk sources accounting for 22% of all URLs shared with political hashtags.

The researchers also found that, unusually in major elections, the political discourse in Sweden tends to be broader in nature, with almost half of all tweets from Swedish users relating to general political issues rather than being linked to particular parties or candidates.

Analysing tweets posted between 8 and 17 August, the study shows that eight of the top ten junk news sources were Swedish and that Russian sources comprised less than 1% of the total number of URLs shared in the data sample.

Junk news sources are defined by the researchers as deliberately publishing misleading, deceptive or incorrect information purporting to be real news about politics, economics or culture. This type of content can include various forms of extremist, sensationalist and conspiratorial material, as well as masked commentary and fake news.

Fabian Sinvert from the Oxford Internet Institute and Freja Hedman from Lund University in Sweden, who led the research, said: ‘This study had a surprising outcome and the results – specifically the amount of general political content and junk news shared – were unique in comparison to the other European countries that we have studied.

‘In both the US and Sweden, the ratio between major news networks and junk news is roughly two to one. Additionally, the top three junk news sites in Sweden are mimicking the look and sound of major news networks. This may make it harder to identify them as junk news for uncritical readers.

‘Of particular interest was the finding that of the ten most-shared junk news sources during the Swedish election, eight were domestic. This is important as it suggests that when combating misinformation, the focus should be domestic rather than looking at foreign junk news.’

Professor Phil Howard, Director of the Computational Propaganda Project at the Oxford Internet Institute, Oxford University, said: ‘The results of this study are notable because they show that compared with the other big elections in Europe over the past year – in France, Germany and the UK – Swedish users are sharing by far and away the most junk news of all.

‘On the one hand, Swedish Twitter users are much less likely to reference particular candidates and parties in favour of sticking to issues. But on the other hand, they have more suspicious sources for their information, and the top three junk news sources account for the vast majority of that misinformation.’

Co-author Lisa-Maria Neudert, also of the Oxford Internet Institute, added: ‘Our study shows that in Sweden, junk news is far from an issue at the fringes of the political spectrum, but instead has emerged as a mainstream phenomenon. Swedish social media users widely shared junk news; the top three sources, all homegrown Swedish outlets, accounted for more than 85% of junk news shares.’