Scott Morrison has also warned Russia's stalled attempts to conquer its neighbour will prompt an even more violent response from the Kremlin, as President Vladimir Putin escalates his threats.

Speaking after a meeting of the national security committee on Tuesday, Mr Morrison revealed Australia will provide nearly $70 million in "both lethal and non-lethal defensive aid" to Ukraine.

The Prime Minister said the bulk of the money will go towards lethal supplies, including missiles and ammunition, as part of a NATO-coordinated support package.

"[Ukrainian] President Zelensky said 'Don't give me a ride, give me ammunition'. That's exactly what the Australian government has agreed to do," he told reporters in Canberra.

"I am not going to go into the specifics of that, because I don't plan to give the Russian government a heads up about what is coming their way.

"But I can assure them: it is coming your way."

Australia has joined an international effort to target Mr Putin and Russian oligarchs, a key powerbase in Moscow, with sanctions over the past week.

Mr Morrison insisted the move was having a "very serious impact" on the Kremlin's ability to maintain its war efforts, as the Russian ruble plummeted to record lows.

"They have self-selected themselves as a pariah state. That's how they should be known all around the world. No-one should have anything to do with them, frankly," he said.

Mr Putin has responded to the international pressure by ramping up threats, on Monday placing Russia's nuclear arsenal on high alert.

The Kremlin has also been accused of using a 'vacuum bomb' - barred under the Geneva Convention - and cluster munitions in civilian areas.

Mr Morrison warned Moscow was likely to escalate violence as Ukrainian forces stymied its attempts to seize Ukraine, with satellite images appearing to show a 60km-long Russian convoy bearing down on Kyiv.

"Anyone who thinks the Russian government is just going to sit there, I think, doesn't understand the intent and the outrageous objectives of President Putin," he said.

Australia also increased support to assist visa approvals for Ukrainian refugees to cope with an ongoing humanitarian crisis, with half a million Ukrainians having already fled their homeland.

But Defence Minister Peter Dutton said Australians should expect the "human tragedy" to worsen.

"We know from history that Russian troops can be particularly brutal," he said.

"I think people should brace themselves for what we will see out of the Ukraine in the coming days and weeks."

It comes after Ukrainian President Volodymyr Zelensky urged international arrivals to take up arms against Russian forces, creating a foreign legion to fight alongside the country's military.

Ukraine's embassy in Canberra has revealed at least 20 people in Australia have expressed an interest in travelling to the region to fight.

But Mr Morrison urged Australians not to travel to Ukraine, warning they faced death or potential legal ramifications on their return.

"That's my very clear message: don't assume it is [legal]. On the evidence we have, it is unlikely," he said.

"What I'd also argue is anyone seeking to do that would find themselves on the wrong end of some very, very violent attacks ... Others have described those sorts of things as suicide missions, and that's not an unreasonable assessment."

Mr Morrison confirmed no Australians attempting to travel to Ukraine had been stopped by the Australian Border Force since Russia's invasion last week.

Labor has voiced its support for designating parts of Ukraine as a declared area for foreign fighters.

The designation, which would make it illegal to enter the region, was applied to parts of Syria amid fears battle-hardened Islamic State militants would pose a security risk after returning to Australia.

The presence of extremist groups in eastern Ukraine has sparked fears among analysts that the region could become a hotbed of terror.

A small number of Australians were believed to have traveled to Ukraine for training with pro-Russian separatists in recent years.

Ukrainian neo-Nazi group the Azov Battalion has also reportedly used the Russian invasion as a recruitment drive online.

The group began as a far-right militia, but has been folded into Ukraine's official armed forces as the country fought pro-Russian separatists.