Facebook has uncovered and deleted dozens of accounts and pages originating in Iran that were intended to provoke division in the US and the UK.

The accounts, which posed as US and UK residents, posted frequently about politically divisive subjects, including race relations, opposition to Donald Trump, and immigration. More than a million Facebook users had engaged with the 82 pages, groups and accounts that were identified, most of them in the US, and Nathaniel Gleicher, Facebook’s head of cybersecurity policy, said they were created to deliberately “sow discord”.

“Our investigation is still in its early days,” said Gleicher, in a press briefing on Friday morning, “and while we have found no ties to the Iranian government, at this point we can’t say for sure who is responsible.”

Seven events were also identified as part of the campaign, but Gliecher did not provide any additional information about them, including whether or not they actually took place. He said the team was still investigating the details and that as they learned more they would release the information. “Based on our analysis and what we have seen so far, the primary focus of the operation was messaging through the large pages and it wasn’t as focused on the events.”

He explained that teams working for Facebook’s newly launched “war room” had identified “inauthentic behavior” from the accounts late last week, and had alerted law enforcement agencies and researchers before removing them.

He emphasized that, ahead of the 2018 midterms elections in the US, their investigative teams were working hard to ensure the platform is not used as a tool for foreign interference. “We work closely with the US government, and we have been in contact with law enforcement, both with the foreign influence taskforce at the FBI and the Department of Homeland Security,” he said, adding that the company’s war room is preparing to work with state election officials if additional issues are uncovered in the coming weeks. “As we lead into the final days before the midterms, our expectation is that they will be seeing challenges.”

Facebook ‘can’t say for sure who is responsible’. Photograph: Facebook

Twice over the summer, Facebook uncovered fake accounts being used by foreign actors to affect American opinions. In July, the social network removed 32 pages and accounts from Facebook and Instagram, with ties to a Russian agency. A month later, Facebook removed 652 fake accounts and pages, created as part of four separate campaigns, that were found to have ties to both Russia and Iran.

Gleicher said the accounts taken down this week had some overlap with those campaigns. The August accounts were originally flagged by the cybersecurity company FireEye, which reported that the intent appeared to be to engender support for Iran-focused US policies, and “to promote Iranian political interests, including anti-Saudi, anti-Israel and pro-Palestinian themes”.

The campaign revealed on Friday, which included accounts that date back to 2016, was largely based around divisive topics in the US and UK that could potentially sway opinions in the upcoming election.

Facebook’s war room was created to investigate these types of activities, Gleicher said, and their teams of roughly 2,000 data scientists, engineers, and investigators are now working closely with the government, law enforcement, and security experts to detect fake accounts.

The social network has come under harsh scrutiny over foreign actors’ attempts to use it to sway the results of the 2016 US election. Last year, Facebook reported that roughly 126 million Americans may have engaged with Russian-backed accounts, which posted divisive content and fake news ahead of the election.

Since then, the company has ramped up efforts to find and remove fake accounts, especially those with ties to foreign actors seeking to interfere in elections. Critics have voiced concerns that the company is still not doing enough to combat fake news and intentionally misleading accounts.

“We face smart, well-funded adversaries, who will never give up, and who constantly change tactics as we improve,” Gleicher said. “We will need to continue to invest heavily in safety and security, not only to prevent election interference on Facebook, but also to protect the authenticity of the connections and conversations across our services.”