A coordinated disinformation campaign targeting the Australian media has been directly linked to Russia and is ramping up ahead of the US presidential election, according to a report.

Finnish analytics firm CheckFirst unmasked the influence campaign, dubbed Operation Overload, in June after a joint investigation with AAP FactCheck and dozens of other global media organisations.

The operation has targeted 15 local organisations, including AAP, the ABC, The Conversation and The Daily Aus, with at least 71,000 spam emails containing deceptive content about global events such as the Ukraine War and the Paris Olympics.

CheckFirst chief executive Guillaume Kuster said digging in the “grey zone” had uncovered more evidence that the campaign was Russia-based.

He said some of the email accounts used were accessed from Russian IP addresses, and QR codes sent in emails were created by an individual connected to a Russian marketing agency.

“That is a red flag,” Kuster said.

“It’s not proof of anything, but it’s one more hint at the fact that that particular organisation is belonging to a wider scope organisational effort.”

He said it was unclear exactly who was behind the campaign or if it was state-backed, but it appeared to be an attempt to trick fact-checkers into debunking and inadvertently amplifying fake content.

“Any publicity is good publicity,” Kuster said.

The number of emails has trebled since June, with the subject shifting to the US election and US newsrooms becoming the prime targets.

Kuster said Australian newsrooms had been targeted because they belonged to “the global West”.

Dr Mathew Sussex, from the Australian National University’s Strategic and Defence Studies Centre, said Russia was interested in Australia due to its support for Ukraine.

“Australia is seen potentially as a bit of a test case of a stable democratic state where you can try out various attempts at disinformation, cyber-enabled political warfare, and see what works and what doesn’t,” he said.

Sussex said targeting fact-checkers was part of a sophisticated strategy of interfering with democratic elections, which included paying US social media influencers to produce pro-Kremlin content.

“If you can swamp fact-checkers and journalists with mis- and disinformation, then that’s another piece of the puzzle,” he said.

Dr Olga Boichak, a University of Sydney disinformation expert, said Operation Overload fitted the Russian doctrine of reflexive control, which aimed to alter an adversary’s information environment.

She said overloading fact-checkers and journalists with deceptive content undermined two mechanisms that created facts in democracies, making it easier to spread disinformation.

“It’s almost like flooding the signal with so much noise that it becomes nonsensical,” Boichak said.

The Department of Home Affairs is aware of Operation Overload, saying it had laws and “a robust framework” to combat influence campaigns.

“Foreign interference and espionage are among Australia’s principal security concerns,” a spokesperson said.

“They threaten the things we value most about our country – our social cohesion, our trusted democracy, and our freedom of thought and expression.”