Any Chinese help offered or given to Russia would be an "abomination", Prime Minister Scott Morrison says.
Mr Morrison has called on China to be transparent about its relationship with Russia as the United States raised concerns about the prospect of financial and military aid flowing through to the Kremlin.
"What is their relationship with Russia, when it comes to throwing them an economic lifeline during this global crisis? And potentially, what, if any, support has been discussed for military support for Russia?" Mr Morrison said.
"Because that would be an abomination."
The prime minister said he remained disturbed by the "chilling silence" echoing in Beijing following Russia's invasion of Ukraine.
The former director of the Defence Intelligence Organisation says Australia shouldn't underestimate the relationship with the pair operating in a quasi-alliance.
Russia is supplying Beijing with high-performance, leading-age technology, including quiet diesel-electric submarines and one of the world's best air defence systems, Professor Paul Dibb said.
Russian President Vladimir Putin has also agreed to build China a ballistic missile early warning radar which would make America's capacity to penetrate nuclear missiles into China a bit more complicated, Professor Dibb told the National Press Club in an address on Wednesday.
He said the Chinese president would be closely monitoring Western actions against Russia and assess how aggressive it can become towards Taiwan without provoking retaliation.
"Xi Jinping will be scrutinising in exquisite detail how much Putin is getting away with the use of military force against a sovereign country across sovereign boundaries," he said.
But Beijing is unlikely to push Russian support too far and risk escalating tensions with the US, former defence department secretary Dennis Richardson said.
"China will support Russia, but I think it will measure out the support in a way that probably keeps it below what might be the sanctions threshold for the US," he said.
"China will operate in a grey area, in a murky area, and it will be difficult to actually catch China with its hands in the till sufficient for sanctions to be imposed."
But while unambiguous support for Russia may appear improbable, decoupling the so-called "unholy alliance" between the authoritarian states with threats is equally unlikely, according to Professor Dibb.
"The issue is we obviously can't now have any prospect in the long foreseeable future of detaching Russia," he said.
"Can we somehow detach China? I'm going to say, my initial reaction to that is - dream on."
Labor leader Anthony Albanese criticised Beijing for failing to condemn Russia's invasion and offering Russia economic lifelines as global sanctions began to cripple its economy.
"China has a responsibility to call out Russia's behaviour and its aggression," Mr Albanese said.
"It's outrageous. It's against international law and it should be called out by all countries, including China, which has a particular responsibility due to its closeness to Russia and also because it's a permanent member of the United Nations Security Council."
