Voice to parliament supporters have been warned to move their signs away from polling booths over concerns they might mislead voters.
Signage from the Yes23 camp has been spotted near voting centres with the same purple colour used by the Australian Electoral Commission.
Early voting in the voice referendum opened on Monday, ahead of polling day on October 14.
In a statement, the commission said it became aware of campaign signage at an early voting centre that could mislead voters.
"To be absolutely clear - the signs were erected by the Yes23 campaign, not the AEC," it said in a statement.
"This combination of using purple and white colours in proximity to AEC signage could mislead a voter about the source of the signage, and by extension, the source of the message on the signage."
The commission said when it became aware of the situation it requested the Yes23 campaign move its signs away from AEC signs.
"The Yes23 campaign has agreed to comply with this request," the commission said.
The 'yes' campaign signs had been marked with the authorisation statement required by law, it added.
A 'yes' campaign spokeswoman said: "Yes23 was made aware of this by the AEC and will rectify the situation."
The Liberal Party faced criticism for the use of signs written in Chinese during the 2019 federal election, which used colours similar to the commission's.
The commission does not have the authority to remove any sign that is more than six metres from the entrance to a polling booth.
If a sign may be in breach of the Electoral Act, the commission can ask someone to remove it or seek an injunction from the courts.
Tess Ikonomou - AAP