Twitter has removed 130 fake accounts linked to Iran which were trying to influence reaction to the first US presidential debate.
The social media site deleted the accounts after the FBI informed them they were trying to “disrupt public conversation” as Donald Trump and Joe Biden went head-to-head.
Twitter said: “Based on intel provided by the @FBI last night we removed approximately 130 accounts that appeared to originate in Iran.
“They were attempting to disrupt the public conversation during the first 2020 US Presidential Debate.”
The site added: “We identified these accounts quickly, removed them from Twitter, and shared full details with our peers, as standard.
“They had very low engagement and did not make an impact on the public conversation.”
Twitter did not say in which way the tweets sought to disrupt public discourse but the tweets did not appear to be advocating for one candidate in particular.
One tweet questioned the political affiliation of Fox News host Chris Wallace, another suggested a "Biden Harris Landslide Victory!" was "#StupidityIn4Words" and one referenced far-right group the Proud Boys.
The FBI said in a statement it gave information to Twitter to curtail “foreign threats”.
"Although we cannot discuss the specific information provided, the FBI regularly shares information with social media companies so they can better protect their platforms," a spokesman said.
"The FBI is actively engaged with our federal partners, election officials and the private sector to mitigate foreign threats to our nation's security and our elections."
Twitter has been ramping up efforts to clamp down on foreign interference ahead of the election.
The company will also increase "login defences to prevent malicious account takeover attempts” of high-profile politicians and political journalists.
Iran has long been a source of concern for Twitter and is one of several countries US authorities are monitoring for potential interference in the presidential election using online disinformation campaigns.
Other countries include Russia and China.
National Counterintelligence and Security Centre director William Evania said in August Iran was “seeking to undermine US democratic institutions, President Trump, and to divide the country in advance of the 2020 elections."
He added that Tehran’s motivation was “driven by a perception that President Trump's re-election would result in a continuation of US pressure on Iran”.
It comes as the commission that oversees US presidential debates says it will change the rules after the first debate descended into chaos as Mr Trump and Mr Biden bickered and traded insults.
The fallout has also been dominated by remarks Mr Trump made about the Proud Boys.
He suggested the group “stand down and stand by”.