Facebook has removed dozens of accounts linked to Iran for spreading disinformation to more than a million followers in the UK and US.
Around 82 pages, including groups and accounts, were deleted after posting about topics such as race relations and immigration in a pattern of "coordinated inauthentic behaviour," the social media giant said.
It comes after the social network removed hundreds of pages, groups and profiles linked to Iran which posed as news organisations or activists in the English-speaking world in August.
Some posts targeted Prime Minister Theresa May and Labour leader Jeremy Corbyn, while others attacked US President Donald Trump.
Facebook, which has more than two billion users, detected the suspicious activity around a week ago, with the US midterm elections coming on 6 November.
Nathaniel Gleicher, Facebook's head of cyber security, said: "Our threat intelligence team first detected this activity one week ago.
"Given the elections, we took action as soon as we'd completed our initial investigation and shared the information with US and UK government officials.
"Despite attempts to hide their true identities, a manual review of these accounts linked their activity to Iran.
"We also identified some overlap with the Iranian accounts and pages we removed in August," he continued.
Writing on the company's blog, Mr Gleicher added that they have found no ties between the accounts and the Iranian government and can't say for sure who is responsible.
Around one million accounts followed at least one of the now-deleted pages, while around 25,000 accounts joined at least one of the groups.
Facebook said it has more than 20,000 people working on "safety and security" while advances in artificial intelligence mean more fake accounts are being spotted.
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It comes after it was revealed on Thursday that the company was fined £500,000 – the maximum possible – over the Cambridge Analytica scandal in which user data was harvested from tens of millions of people.
The UK's information commissioner imposed the fine for "serious breaches of data protection law" and around one million people were affected in the UK.