Ukraine has retaken ground in the nation's east, forcing a Russian retreat from some previously seized territory.

Russia is attempting to formalise its annexation of parts of Ukraine by holding referendums on separation, which have been labelled a sham and illegitimate by much of the international community.

Mr Marles branded the Russian president's threats as appalling.

"We've seen president Putin go there before and it is a real concern that he should be speaking in this way," he told reporters in Canberra.

Ukraine has requested military aid from Australia in the form of further Bushmaster vehicles and artillery.

The opposition is urging the government to provide the assistance expeditiously.

Opposition Leader and former defence minister Peter Dutton said Mr Marles needed to cut through any bureaucratic red tape he was facing from the Department of Defence.

"We want to get equipment, support, defence material in the hands of the Ukrainians as quickly as possible," Mr Dutton told the Nine Network.

"This is the time for the world to stand up, to be heard, and to speak with a loud voice against these acts of aggression."

Mr Marles said the conflict was expected to be protracted and the government would continue to work with Ukrainian officials to provide ongoing support.

Ukrainian ambassador to Australia Vasyl Myroshnychenko said there shouldn't be any escalation in the conflict as long as Mr Putin didn't resort to the use of weapons of mass destruction.

But Mr Myroshnychenko acknowledged the conflict would likely get worse before it improved.

"We need more (support) because this is getting difficult," he told ABC TV.

"We need more artillery and fighting drones and more Bushmasters."

Labor MP Peter Khalil, the chair of parliament's intelligence and security committee, said there were encouraging signs from nations - including China and India - that had largely remained neutral to the conflict.

Mr Putin has acknowledged his Chinese counterpart Xi Jinping raised concerns about the war with him.

Mr Khalil said he found the acknowledgement to be an odd admission and it led him to question if the Chinese government was unhappy with the way the Russian leader was prosecuting the war.

"Is (China) trying to push them in a different direction? Have they sort of moved away from Putin to a certain extent?" he told Sky News.

"President Xi has a lot of power over Putin. If China pulled the rug out from underneath Russia, this wouldn't really be able to continue."

Foreign Minister Penny Wong says she used a meeting with her Chinese counterpart Wang Yi on the sidelines of the United Nations to raise Beijing's lack of Russian condemnation.

"China is a great power. China has, like all of us, signed up to the UN Charter," she said.

"We encourage China ... to use its influence to end the war.

"We cannot allow Mr Putin's irresponsible threats to be successful in shaping an outcome which goes to Ukrainian sovereignty being abrogated."

Australian Associated Press