Money from a crowd-funding campaign to pay for anti-same-sex marriage skywriting over Sydney has been frozen, its anonymous organisers say.
The words "vote no" appeared four times over the city on Sunday morning, a day after the Coalition for Marriage launched its campaign against same-sex marriage.
But the group, which is the main body opposing any reform of Australia's marriage act, denied responsibility and told AAP it was a grassroots action.
The message appears to have been funded through a Go Fund Me page which raised more than $2500.
One woman donated $1000 to the cause.
The anonymous author of the page declared it was "time for traditional Australian's (sic) to take a stand".
"It's time we all sent a clear message that we will not put up with our way of life been (sic) deconstructed any further," the page said.
The author later announced the money had been frozen by the website "until we give our names and locations".
The page was inundate with messages of condemnation.
"I feel sorry for all of you," one woman wrote.
"What an awful way to live your lives. I can't imagine being so hateful."
Organisers said they were "keen to stay fairly anonymous" and defended their actions.
Flight tracking information confirms the skywriting was performed by a Cessna owned by Skywriting Australia, whose charges start from $3990.
Social media users began to circulate the company's contact information and posted the abusive messages they'd sent.
The company has not responded to requests for comment.
Senator Cory Bernardi, who spearheaded the Coalition for Marriage's campaign launch in Sydney on Saturday night, declared opponents of change were on the "right side of legal and moral history".
Almost half of all Australians eligible to take part in the national postal survey on same-sex marriage should have received their ballot this week, a Senate inquiry heard on Friday.
Results are expected on November 15.