Twitter bots are proliferating ahead of Sweden's election next month - and they are 40 per cent more likely to support the anti-immigrant Sweden Democrats than human users. That's the finding of the country's Defence Research Agency, which says the social media platform has moved to suspend many of these malicious accounts.

Democracies across the world need to prepare for this threat: Radical parties, with or without external help, are using and perfecting this form of digital propaganda - because it appears to work so well.