The Yes23 campaign has been issued a warning by the Australian Electoral Commission for signage at a Voice referendum voting centre that "could potentially mislead voters".
The purple 'Vote Yes' signs with white writing bear a similar shade as the AEC's signage and branding.
A photo posted on X, formerly Twitter, showed the signs near AEC's purple voting centre sign.
They were also displayed at a polling place visited by Yes23 campaign director Dean Parkin and Independent Member for Kooyong Monique Ryan in Melbourne on October 2.
The AEC said it was first alerted to the signs on October 2 when early voting began in some states.
"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 AEC said.
"Accordingly, when we were alerted to this signage the AEC requested the Yes23 campaign to rectify the situation by ensuring their signs are not placed in the proximity of AEC voting centre signs.
"The Yes23 campaign has agreed to comply with this request."
A campaign spokesperson said Yes23 was made aware by the AEC and would rectify the situation.
Prime Minister Anthony Albanese was asked about the signs during a Hobart press conference.
"There are a range of colours apparently in posters, people have seen that in t-shirts etc so they have the full range of colours - [the campaign will] comply of course with anything from the AEC," Mr Albanese said.
The AEC said it had been clear for a number of years that it preferred campaigners not use a purple and white combination in a way that could be misleading.
A court found signs used during the 2019 federal election campaign in parts of Melbourne were likely to mislead or deceive voters, in part for using the similar purple colouring.
But the AEC has no legal authority to remove signs that are more than six metres from the entrance to a polling booth.
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It can only request for the signs to be removed and seek an injunction if they aren't.
Following the 2019 judgement the AEC "strongly urged" future campaigners not to use the colour purple or other branding in a way that looked to be imitating the AEC.
The purple 'Vote Yes' signs are not new to the Yes23 campaign but caught the attention of the AEC once early voting centres opened on October 2 and 3.
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