A fake Facebook post in which Opposition Leader Alistair Coe appeared to label climate change a "conspiracy" was shared by high profile Canberrans before being deleted.
Mr Coe said he had contacted Elections ACT about the post, which has come during an election year.
The post said people like Labor leader Anthony Albanese and Greens leader Adam Bandt had attempted to bring "cheap politics into the devastating (bushfire) crisis by blaming the climate change conspiracy rather than the real cause".
It was originally posted on Reddit before being widely shared on Twitter on Sunday, including by politicians and Unions ACT.
Greens ACT leader Shane Rattenbury was among the people to be caught out by the fake post.
Mr Coe said it was disappointing high profile people had shared the post without seeking to verify it first.
"The dirty tricks for this campaign have unfortunately started very early," he said.
"We're still eight or nine months away from polling day yet the fake posts and fake news is unfortunately alive and well in the ACT.
"Who knows who will be a victim of it tomorrow.
"The reality is there is a need in integrity in all reporting, be that by journalists or of course in the promotion of social media posts."
Mr Coe said the Canberra Liberals contacted people who were promoting the post, who removed it and apologised.
He said the party would contact Elections ACT about how future situations could be managed.
"Everyone in the ACT expects a higher standard from public officials and I hope this serves as a very valuable lesson for everybody, that you've got to be somewhat skeptical about what you read online and if it seems like it's a falsehood, there's a fair chance it is."
Mr Rattenbury said it was not a surprise the tweet was widely shared considering the Liberals' climate change policies.
But he said everyone needed to be more careful to authenticate information.
"Sadly, 'fake news' is a global trend, and it's disconcerting to see this emerge in local politics," he said.
"Ahead of an election year, it's clear we'll all need to be more vigilant in verifying third-party sources.
"'Fake news' works best when it cuts close to the truth.
"Given the stance of the Liberals locally and nationally when it comes to climate change, it's no surprise that this tweet spread so quickly."
Mr Coe has also been the subject of a campaign against him from a new Facebook page, Let Coe Know; Time to Act Scomo.
But Mr Coe maintains his leadership is safe and the party is united.
It came after a group of disaffected Liberal MLAs made a leadership coup attempt in November, amid fears Mr Coe was too socially conservative for the Canberra electorate.
Moderate Elizabeth Lee was touted as a possible alternative.
- Correction: An earlier version of this story included an error in the title of the Facebook page critical of Alistair Coe.