Police are investigating reports of a "no" campaign volunteer displaying a Nazi symbol at the entrance of a polling location.
Officers were called to Lyneham Primary School about 11am on Saturday.
The Canberra Times spoke to multiple witnesses who said they saw a Nazi-affiliated symbol on the back of the man's bike.
One person described the symbol as being displayed on what resembled a large number plate.
Witnesses said the bike in question belonged to a man wearing a "no" campaign t-shirt who arrived at the polling booth before 8am.
He is said to have locked the bike up to a fence before handing out leaflets to the Voice referendum voters.
ACT Policing confirmed they received these reports.
"By the time ACT Policing officers arrived at the booth, the man had left the scene and investigations are ongoing," an ACT Policing spokesperson said.
Precisely what symbol was displayed remains unconfirmed.
Two witnesses said they recognised it to be the Black Sun, or sun wheel, an ancient symbol appropriated by Nazis.
Police were reportedly called after multiple people walking into the polling booth recognised the symbol and complained to Australian Electoral Commission staff.
Witnesses said one person left visibly upset after confronting the man who owned the bike.
"Anyone with information about the incident or the man is asked to call Crime Stoppers on 1800 333 000. Information can be provided anonymously," an ACT Policing spokesperson said.
