ATLANTA, United States (AFP)— The Federal Bureau of Investigation (FBI) warned of bomb threats at polling stations in “multiple” US states on a tense Election Day, adding that none were credible but many appeared to originate from Russia.

The statement from the FBI came as authorities in the US state of Georgia said hoax bomb threats had briefly disrupted voting there Tuesday.

The 2024 US presidential campaign has been a particularly volatile one, and security for Election Day has been ramped up to unprecedented levels given concerns over possible civil unrest, election chicanery and violence against poll workers.

“The FBI is aware of bomb threats to polling locations in several states, many of which appear to originate from Russian email domains,” spokeswoman Savannah Syms said in a statement.

“None of the threats have been determined to be credible thus far,” she added, urging the public to “remain vigilant.”

Georgia’s secretary of state Brad Raffensperger said the state had also identified the source of bomb threats that briefly disrupted voting at polling places.

“It was from Russia,” he said, without elaborating.

At least seven polling stations in Georgia’s Fulton County were among those facing threats and were briefly closed, South Fulton’s Mayor Kobi told AFP.

“None of the polling places were closed for more than 30 minutes,” he told AFP outside one of them — Feldwood Elementary School in South Fulton.

“There are some people who are trying to discourage people in South Fulton from voting, but we are the Blackest city in the United States,” he said.

“We are the descendants of, the sons and daughters of people who faced lynch mobs, water cannon… to exercise the right to vote. And so we aren’t going to let bomb threats turn us around.”

With Democrat Kamala Harris and Republican Donald Trump deadlocked at the climax of the 2024 race, authorities are keen to reassure jittery Americans that their votes are secure. But they have also bolstered physical security for election operations nationwide.

Poll workers have been given panic buttons, workers, special weapons teams have been deployed on rooftops, and hundreds of National Guard personnel have been placed on standby.

The FBI set up a national election command post in Washington to monitor threats 24 hours a day through election week, and security has been bolstered at many of the nearly 100,000 US polling stations.

The US Capitol Police, who protect the seat of Congress in Washington, said on social media platform X Tuesday that they had arrested a man who “smelled like fuel, had a torch & a flare gun.”

He was stopped at the Capitol visitor centre — part of the complex that was stormed by Trump supporters in a deadly riot on January 6, 2021 as they sought to overturn his election loss to Joe Biden.

The visitor center would remain “closed for tours for the day, while we investigate,” the post said.

The bomb threats were not the first time US authorities have pointed the finger at Russian interference during the vote.

Hours before polls opened, officials warned that Russia-linked disinformation operations had falsely claimed attempts were being made in battleground states to fraudulently sway the outcome of the election.

And on Friday, US intelligence officials blamed Russia for a fake video of a Haitian immigrant claiming to have voted multiple times.

The United States previously imposed sanctions on Russian individuals and entities over alleged attempts to interfere in the 2016, 2018 and 2020 elections.