Right-wing groups from the United States have attempted to undermine Chancellor Angela Merkel's re-election campaign, according to German researchers.
The researchers started out looking for evidence of Russian interference, but have instead found activity that appears to be linked to American white supremacists and neo-Nazis, reported USA Today.
"So far we have not been able to track down any specific Russian activity," said Simon Hegelich, a professor of political science data at the Technical University of Munich. "A lot of the stuff we are seeing in Germany can be linked to, or is at least inspired by, the 'alt-right' movement in the U.S."
Hegelich and other researchers said anonymous trolls have been spreading right-wing themes to German voters through YouTube, 4chan, Reddit and other social media platforms.
The posts criticize Merkel, who is seeking a fourth term, and her conservative Christian Democratic Union party, and her chief rival, Martin Schulz of the left-of-center Social Democratic Party.
Many of the posts originate in the U.S., and are tagged with the candidates' names or #altright.
One researcher found Facebook searches for political discussion groups in Germany are steered toward right-wing parties, which he said made little sense.
"It's really strange because Facebook says this should be impossible because you are only supposed to get recommendations based on your own 'friends,' 'groups' and 'likes,'" said Sandro Gaycken, of the Berlin-based Digital Society Institute. "But everyone in Germany is getting these right-wing party recommendations."
Facebook has responded by temporarily turning off the category "news and politics" in its discover tab while the social media company investigates.
Researchers say there's no evidence to show outside hackers are attempting to promote one candidate over another, unlike Russian efforts in the U.S. election.
"There is no 'pro-Putin' candidate," said Mark Galeotti, who runs the Center for European Security. "Any interference would be unlikely to have any substantive impact on the election result and only harden Germany's position against Moscow."
Neo-Nazis boasted of their efforts shortly after the election of President Donald Trump.
"There will never be an election again in which trolling, hacking and extreme far-right politics do not play a role," wrote Andrew Auernheimer, a hacker and blogger for the neo-Nazi Daily Stormer website.