The Australian Electoral Commission is investigating a series of doctored posters that have appeared overnight incorrectly showing the names and faces of "teal" independent candidates with the Greens logo.
The posters, featuring photos of Zali Steggall, Sophie Scamps and Georgia Steele with the Greens logo, appeared in the New South Wales electorates of Mackellar, Warringah and Hughes overnight.
Similar posters have also appeared in Hume, south-west of Sydney, targeting independent Penny Ackery.
It is not clear who produced the signs because they display no authorisation statement as required by electoral law.
The posters have been put up all over the Sydney electorates, often cable tied alongside the candidates' legitimate corflutes.
Unauthorised stickers have also appeared in the Melbourne electorate of Kooyong this morning, where independent Monique Ryan is challenging Treasurer Josh Frydenberg.
The stickers claim a vote for Ms Ryan is a vote for Labor.
In a statement, Greens leader Adam Bandt said the posters had no connection to the party and the matter had been referred to the AEC.
"There's a good chance that whoever is behind this has also committed a criminal act," Mr Bandt said.
"These doctored corflutes … seem to have no other purpose other than to mislead voters."
The AEC said it had received several reports about the matter and was taking it "extremely seriously".
"It appears to be unauthorised signage in breach of the Commonwealth Electoral Act 1918. We are endeavouring to find information regarding who is behind the signage," an AEC spokesperson said.
The poster campaign has received a strong response from the independent candidates and their volunteers.
Ms Steggall said she believed this was a "coordinated attack campaign targeting independents".
"With just two weeks to go until polling day, my opponents are going low — very low," she said.
In a statement, Dr Scamps said the posters were "distressing and upsetting" to many of her campaign volunteers and supporters.
"Instead of wasting our time on dealing with illegal attacks on property, I want to focus on listening to the people of Mackellar and representing them on the issues that matter most."
Ms Steele said on Facebook that her campaign corflutes had been shredded and stolen last night and replaced with the fake Greens posters.
"We are running a positive campaign powered by the community," she said in a statement. "We won't be swayed by bullies."
Advance Australia, which has run authorised billboards in Warringah targeting Ms Steggall over her support of transgender women, strongly denied being behind the unauthorised posters.
"All material produced by Advance is clearly authorised and strictly complies with AEC rules," a spokesperson said.
A cohort of mostly female independent candidates are facing off against Liberal candidates in several key seats across the country.
The candidates, who are focused on issues including climate change and establishing a national integrity commission, have the backing of the Climate 200 group, set up by businessman and political activist Simon Holmes à Court.
The accusation that the independents are Labor or Greens operatives "in disguise" has been a consistent line of attack from their political opponents, which the candidates have strongly rejected.
Advance Australia, for example, has run authorised social media ads that show Ms Steggall pulling back her shirt to reveal the Greens logo.
