China has denied it is behind cyber attacks on Australian business and government organisations, saying such suggestions are "baseless".
But an Australian think tank is standing by its claim the attacks almost certainly came from the Asian superpower.
Prime Minister Scott Morrison on Friday confirmed Australia has been the target of increased cyber attacks by a foreign entity, describing it as a "sophisticated, state-based cyber actor".
He declined to put a name on which country is carrying out the attacks, and nor would Opposition Leader Anthony Albanese, who was briefed by Australia's security agencies.
The Australian Strategic Policy Institute said the attack was "95 per cent or more" likely to have been launched from China because of the scale and intensity of the attack.
But Chinese Foreign Ministry spokesperson Zhao Lijian dismissed such allegations, and took particular aim at ASPI.
"The attacks coming from institute against China are totally baseless nonsense," Zhao told reporters at a daily briefing and claimed ASPI is backed by US arms companies.
ASPI executive director Peter Jennings said China's response was "laughable nonsense".
Asked on ABC television why ASPI was singled out when other experts have also hinted the attacks came from China, Mr Jennings said the institute has done a range of work the Chinese doesn't like.
This includes analysis on forced labour using prisoners and on the Chinese agency that pushes propaganda both at home and abroad.
"We have freedom of speech which is something that you have also not got in China and I think the Chinese officialdom find that uncomfortable and unusual," Mr Jennings said.
The decision by the Australian government to raise concerns over cyber security comes at a time of growing tensions with China, with the two countries falling out over the origin of the coronavirus, trade, travel and most recently, the death sentence handed to an Australian drug smuggler.
But federal LNP MP Andrew Laming says the "cacophony" of accusations over the cyber attack isn't helping.
"Clearly there was a line in the sand with (the prime minister's) statement, but it's not constructive then for additional commentators to engage in a tit-for-tat," Dr Laming told ABC television.
Labor frontbencher Amanda Rishworth said the priority was for Australian businesses and governments to take precautions against future attacks.
"In some ways, it doesn't matter where these attacks come from, it's the consequence of these attacks," she told ABC television.
"Singling out an individual actor doesn't actually achieve anything."
Australian Associated Press