File Photo: People are silhouetted as they pose with mobile devices in front of a screen projected with a Facebook logo, in this picture illustration taken in Zenica Oct. 29, 2014. (Xinhua/REUTERS)

SAN FRANCISCO, Oct. 26 (Xinhua) -- Facebook has taken down 82 pages, groups and accounts for "coordinated inauthentic behavior" that originated in Iran and targeted people in the United States and Britain, Facebook Head of Cybersecurity Policy Nathaniel Gleicher said Friday.

Facebook said the owners of the accounts on Facebook and Instagram appeared to represent themselves as U.S. citizens, or in a few cases British citizens, and they posted contents on politically charged topics such as race relations, immigration policies and the federal government.

The social media giant said it detected the activities last week and traced them back to Iran, but could not determine who should be responsible.

About 1.02 million users were following at least one of the accounts, an estimated 25,000 accounts joined at least one of these groups, and more than 28,000 users followed at least one of these Instagram accounts, Facebook said.

It added that the Iranian actors spent less than 100 U.S. dollars on two advertisements on both Facebook and its subsidiary Instagram, the first ad appearing in June 2106 and the other in January 2018.

Facebook has in recent months launched massive campaign to fight online misinformation activities by foreign actors ahead of the upcoming U.S. mid-term elections, and has set up an "Elections War Room" where its security employees took all possible means including artificial intelligence technology to combat cyber threat.

"There are now over 20,000 people working on safety and security at Facebook and thanks to improvements in artificial intelligence we detect many fake accounts... before they are even created," Facebook said.

Facebook removed more than 600 accounts and pages in August after it discovered Iran-related accounts were running influencing operations on its platform.

Facebook said it has mobilized powerful teams from across the company, including from threat intelligence, data science, software engineering, research, community operations and legal, to stop foreign misinformation activities targeting U.S. domestic politics.