Two polling locations in Georgia were closed for half an hour following bomb threats. (AP PHOTO)

Hoax bomb threats, many of which appeared to originate from Russian email domains, have been directed at polling locations in five battleground states during voting for the US election, the FBI says.

“None of the threats have been determined to be credible thus far,” the FBI said in a statement on Tuesday, adding that election integrity was among the bureau’s highest priorities.

Polling sites were targeted by bomb hoaxes in Georgia, Michigan, Arizona, Wisconsin and Pennsylvania, and at least two sites in Georgia were briefly evacuated.

The two locations, in Fulton County, both reopened after about 30 minutes, officials said, and the county was seeking a court order to extend the locations’ voting hours past the statewide 7pm deadline.

Georgia Secretary of State Brad Raffensperger, a Republican, blamed Russian interference for the threats.

“They’re up to mischief, it seems. They don’t want us to have a smooth, fair and accurate election, and if they can get us to fight among ourselves, they can count that as a victory,” Raffensperger told reporters.

The Russian embassy in Washington said insinuations about Russian interference were “malicious slander”.

“We would like to emphasise that Russia has not interfered and does not interfere in the internal affairs of other countries, including the United States,” the embassy said in a statement.

“As President Vladimir Putin has repeatedly stressed, we respect the will of the American people.”

A senior US cyber official said her agency had not seen any major incidents reflecting foreign interference in the election despite a steady stream of disinformation aimed at disrupting the vote throughout the day.

“At this point, we are not currently tracking any national-level significant incidents impacting security of our election infrastructure,” Cait Conley, a senior official at the Cybersecurity and Infrastructure Security Agency, told reporters.

Ann Jacobs, head of the Wisconsin Elections Commission, said fake bomb threats were sent to two polling locations in the state capital of Madison, but they did not disrupt voting.

A spokesperson for Jocelyn Benson, Michigan’s Democratic secretary of state, said there had been reports of bomb threats at several polling locations, but none were credible.

Benson’s office had been notified the threats might be tied to Russia, the spokesperson said.

An FBI official said Georgia received more than two dozen threats, most of which occurred in Fulton County, which encompasses much of Atlanta, a Democratic stronghold.

Police in DeKalb County, Georgia – another Democratic stronghold – later responded to bomb threats at seven locations, including five that were polling places and were evacuated.

County officials were seeking an emergency order extending opening times at the voting sites.

A senior official in Raffensperger’s office, speaking on the condition of anonymity, said the Georgia bomb hoaxes were sent from email addresses that had been used by Russians trying to interfere in previous US elections.

Adrian Fontes, the Arizona secretary of state, a Democrat who is the chief election official in the swing state, said four fake bomb threats had been delivered to polling sites in Navajo County.

“Vladimir Putin is being a prick,” Fontes said.

A judge in Clearfield County, Pennsylvania, extended voting hours to 9pm local time after a bomb threat at a vote-counting site disrupted the process.

Josh Shapiro, Pennsylvania’s Democratic governor, said multiple bomb threats had been investigated and none were found to be credible. He did not mention Russia.

Democratic Vice-President Kamala Harris and Republican former president Donald Trump are locked in a tight race to win the White House.

The phoney bomb threats mark the latest in a string of examples of alleged interference by the Russians in the 2024 election.

US intelligence officials have also accused Russia of interfering in previous presidential elections, especially the 2016 race that Trump won against Democratic candidate Hillary Clinton.