A polling station in north London was temporarily cordoned off after officers were called to investigate a "suspect package" reported nearby.
Voters complained after Shepherd's Hill was closed briefly on Thursday morning, affecting access to Highgate Library polling station.
"Just been told I can’t vote at the moment as my polling station and my road are closed due to intel about a possible bomb. We’re hardly the heart of Westminster!" wrote one potential voter in Highgate, which backed remaining in the EU by 75 per cent to 25 per cent in the 2016 referendum.
Police confirmed around an hour later that officers had attended and assessed the item, which was deemed to be non-suspicious.
"The incident has been stood down," Scotland Yard said in a tweet.
It comes as police in Scotland said they were deploying more than 100 extra officers following an increasingly tense and hostile election campaign that has seen clashes between far-right activists and anti-racism protesters.
Deputy Chief Constable Will Kerr, of Police Scotland, said four units comprising the extra staff, would be "strategically placed" throughout the day.
"We do now. The tone is just fundamentally different."
