Canada's public broadcaster said Tuesday it found in a trove of Twitter messages evidence of possible foreign actors trying to sow divisions between Canadians on pipelines, migrants and other hot-button issues.
The Canadian Broadcasting Corporation (CBC) said it identified roughly 21,600 malicious tweets targeting Canadians, mostly sent in 2017, out of 9.6 million scanned.
The troll accounts -- which have since been deleted by Twitter -- are suspected of originating in Russia, Iran and Venezuela.
They retweeted messages from Canadian activists, politicians and media reports highlighting opposition to pipelines after Washington approved construction of a conduit from Alberta's oil sands to US Gulf Coast refineries -- in an apparent attempt to whip up tensions between pipeline proponents and opponents.
They also stoked immigration fears, disseminating strong reactions to the Quebec City mosque shooting and US President Donald Trump's travel ban on Muslim countries, as a wave of asylum seekers showed up at Canada's southern border.
Scholar and Middle East expert Sami Aoun told CBC that Iran, for example, has a strategic interest in seeing North American pipeline projects fail.
"The Iranians are trying to short-circuit American sanctions by selling their oil in Asia. To keep a certain advantage in China and India, they might be trying to prevent Canada from developing pipelines that could give the country better access to those markets," he explained.
Ottawa last month created a special task force to fight disinformation and foreign meddling in upcoming elections, after cyberattacks and interference in US and European ballots.
Prime Minister Justin Trudeau's government -- which hopes to hold onto its majority in the October poll -- also earmarked funding to teach voters how to identify malicious online posts.
Democratic Institutions Minister Karina Gould told a January 30 press conference that Twitter, Google and Facebook have been used to spread disinformation.
"Trolls and bots are dispatched to stoke anxiety, even hysteria around sensitive issues. Fake news masquerades as legitimate information," Public Safety Minister Ralph Goodale warned.
A government briefing document said Ottawa "expects these companies to take concrete actions to help safeguard this fall's election."