Australia will support any war crimes investigation into Russian President Vladimir Putin after the discovery of hundreds of dead civilians on the outskirts of Kyiv.
Defence Minister Peter Dutton has described Russian military action in Ukraine more broadly as "straight up and down the act of a war criminal" who must be held accountable.
Foreign Minister Marise Payne has also supported US President Joe Biden's call for an investigation, prompted by Ukrainian reports of 300 residents killed by Russian forces while Chechen fighters controlled the area.
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Ukrainian President Volodymyr Zelenskyy visited the town of Bucha and said dead people were found in barrels and basements, some having been strangled or tortured, some with severed limbs.
He alleged women had been raped and children murdered.
"You saw what happened in Bucha," Mr Biden told reporters at the White House. "This warrants him — he is a war criminal."
Senator Payne said the reports were beyond horrific and obscene but did not use the term genocide, which was referenced by President Zelenskyy.
"We have seen in the last few days, particularly in Bucha, is the butchering of people in mass graves, the murder and use of rape as a weapon of war," Senator Payne told Channel Seven.
"It must be investigated in the context of the war crimes issues that have been raised [and] Australia stands very strong in relation to that and will work closely with our international partners to ensure that is the case."
On Sunday, Bucha's deputy mayor, Taras Shapravskyi, said that 50 residents had been victims of extra-judicial killings carried out by Russian troops.
The Kremlin has denied any accusations related to the killing of civilians in Bucha.
Mr Dutton said the atrocities in Bucha provided proof that tougher international sanctions were required.
Australia has since banned the export of luxury goods to Russia, in line with action already taken by the European Union and the United States.
"[Mr Putin] is a brutal autocrat and the use of chemical weapons, the use of brutality against women ad children just doesn't faze him," Mr Dutton told Channel Seven.
"When you are seeing theatres bombed, when you are seeing residential areas bombed and the potential of mass graves, of executions, well, that is straight up and down the act of a war criminal and this should be investigated as quickly as possible."
Ukrainian ambassador says more arms needed
Ukraine's new ambassador to Australia, Vasyl Myroshnychenko, said the atrocity highlighted the need for the global community to arm the Ukrainian military.
"If we can't defeat the Russians, they'll continue committing the crimes," he said.
"They're doing so in the territories they're occupying.
Mr Myroshnychenko welcomed the imminent departure of four Bushmaster armoured vehicles from RAAF Amberley, following President Zelenskyy's request to federal parliament last week.
"We were very happy that we received such a prompt response," he said.
"From the day one of the statement of President Zelenskyy and the next day it was confirmed that Australia is ready to supply it.
"That tells a lot about the friendship we're seeing between Australia and Ukraine."
He said he did not have details of any further requests for military assistance from Ukraine to Australia.
The destruction and civilian deaths in Bucha looks set to galvanise the United States and Europe into additional sanctions against Moscow, with officials raising the prospect of restrictions on Russia's energy exports.
"We have to continue to provide Ukraine with the weapons they need to continue the fight. And we have to gather all the detail so this can be an actual — a war crimes trial," Mr Biden said.
