The US Federal Bureau of Investigation (FBI) said on Tuesday that five polling stations in several US states have been targeted by bomb threats, and that most of the threats appear to come from Russian domains.

At least two polling stations in the state of Georgia were evacuated due to the threats, officials said. But they were rewatched after about 30 minutes, and authorities are now awaiting a court ruling to extend voting beyond the nationwide poll closing time of 19 p.m., to make up for the time lost during the evacuation.

Brad Raffensperger, Georgia's secretary of state, said Russia was behind the bomb threats.

"It seems that they have started doing mischief. They don't want us to have good, fair and accurate elections, and if they come out and encourage us to fight against each other, then they count that as a victory," Raffensperger told reporters.

The FBI said in a statement that none of the threats are credible.

Georgia alone has received more than two dozen false bomb threats on Election Day, an FBI official told Reuters.

Earlier in the day, US intelligence and security officials accused Russia and Iran of stepping up cyberattacks and disinformation campaigns they said are aimed at sowing division as Americans vote in the tense presidential election.

Russian-linked influencers “are creating fake videos and articles to undermine the legitimacy of the election, to instill fear in voters about the election process, and to suggest that Americans are using violence against each other because of political preferences," said the announcement issued Nov. 4 by the Office of the Director of National Intelligence, the Federal Bureau of Investigation and the Cybersecurity and Infrastructure Security Agency.

"These efforts risk inciting violence, including against election officials," these agencies said.

US intelligence agencies have warned for months that there are efforts supported by the Russian government to influence the US election, where former Republican President Donald Trump and Democratic Vice President Kamala Harris are facing off.

Pre-election polls suggested the race would be close, raising tensions as voters headed to the polls after a bitter campaign.

Both Tehran and Moscow have denied playing a role in any disinformation campaign during the American presidential elections./REL