Prime Minister Scott Morrison has issued a stern warning to Australians thinking of going to fight in Ukraine.
He said those that did go could be doing so illegally.
“I can understand absolutely the strong feelings and the motivations for people to go and do that,” Mr Morrison said.
“But I would say at this time the legality of such actions are uncertain under Australian law.”
It follows a call by Ukrainian President Volodymyr Zelenskiy on Sunday for foreign fighters to join the resistance against a Russian invasion.
Mr Zelenskiy said the Ukrainian armed forces were in the process of setting up a foreign legion unit for international volunteers.
“Anyone who wants to join the defence of Ukraine, Europe and the world can come and fight side-by-side with the Ukrainians against the Russian war criminals,” he said.
Mr Morrison said it remained unclear exactly what was being proposed by the Ukrainian leader.
“Our law sets out arrangements where people can be involved in official activity by a sovereign state, which Ukraine obviously qualifies for,” Mr Morrison said.
“But the nature of these arrangements are very uncertain.”
The government’s official advice for Australians is not to travel to Ukraine.
Several demonstrations have been held across Australia since the invasion began, largely by Australians with Ukrainian heritage concerned for the future of the country.
On Sunday, The European Union agreed to roughly €500 million ($AUD 776 million) worth of arms and aid to the Ukrainian military.
“For the first time ever, the EU will finance the purchase and delivery of weapons and xjmtzywother equipment to a country that is under attack,” European Commission President Ursula von der Leyen told reporters.
Former Deputy Secretary-General of NATO, Rose Gottemoeller told 730 on Monday the conflict could go on for some time.
“People are ready to stand and fight as individuals not only in the armed forces context,” she said.
“So I do think this is a big risk for Putin and for the Russian military overall, that they could be facing a bloody insurgency over a lengthy time in Ukraine.”