Climate change, Covid and China's "coercion" in the Indo-Pacific top the agenda as foreign ministers of the Quad grouping of Australia, India, Japan and the United States meet in Melbourne on Friday, with talks also covering an escalating crisis between the West and Russia over Ukraine.

US Secretary of State Antony Blinken arrived in Australia this week as Washington grapples with a standoff with Moscow, which has massed some 100,000 troops near Ukraine’s border and stoked Western fears of an invasion. Russia denies it has such plans.

The Biden administration wants to show the world its long-term strategic focus remains in the Asia-Pacific and that a major foreign policy crisis in one part of the world does not distract it from key priorities.

Asked by reporters on Friday if confrontation with China in the Indo-Pacific was inevitable, Blinken replied "nothing is inevitable".

"Having said that, I think we share concerns that in recent years China has been acting more aggressively at home and more aggressively in the region," he said, before meeting with Quad foreign ministers and Prime Minister Scott Morrison.

Australian Foreign Minister Marise Payne said on top of cooperation in the Indo-Pacific, climate change and Covid related issues, the two top diplomats will also be discussing China, North Korea and Ukraine.

"More than one authoritarian regime is presenting itself in the current world climate as a challenge. DPRK (North Korea), China as well and they will be part of our discussions today. We strongly support US leadership on these challenges," she said before a bilateral meeting with Blinken.

"We are going to talk today, I'm sure, about the threats to the sovereignty and the territorial integrity of Ukraine as well," she added.

Britain said the "most dangerous moment" in the West's standoff with Moscow appeared imminent, as Russia held military exercises in Belarus and the Black Sea following the buildup of its forces near Ukraine.

On Thursday, Blinken said Washington was working "24/7" on the Ukraine crisis but reaffirmed US focus on the Indo-Pacific — a region he said would be instrumental in shaping much of 21st century. "It's important that we be present, that we be engaged, that we be leading across this region," he said.

'Free from coercion'

Both Blinken and Payne said a key element of the Quad discussion will focus on establishing a regional environment free from "coercion", a thinly veiled swipe at Beijing's expansive economic and military ambitions in the Indo-Pacific.

The Quad's cooperation on the region's Covid response was "most critical", Payne told parliament, with cyber and maritime security, infrastructure, climate action and disaster relief - especially after the recent Tonga volcanic eruption - also in focus.

Speaking to reporters on the plane en route to Melbourne, Blinken described the Quad as a "powerful mechanism" to deliver vaccines worldwide as well as to push back against "aggression and coercion" in the Indo-Pacific, without naming China.

New pledges are unlikely to be announced before a May summit of Quad leaders in Japan that President Joe Biden plans to attend.

Blinken's trip comes after China and Russia declared last week a "no limits" strategic partnership, their most detailed and assertive statement to work together - and against the United States - to build a new international order based on their own interpretations of human rights and democracy.

US-Chinese ties are at their lowest point in decades as the world's top two economies disagree on issues ranging from Hong Kong and Taiwan to the South China Sea and China's treatment of ethnic Muslims.

Biden told Asian leaders in October the United States would launch talks on a new Indo-Pacific Economic Framework. But few details have emerged and his administration has been reluctant to offer the increased market access Asian countries desire, seeing this as threatening American jobs.

Critics say the lack of US economic engagement is a major weakness in Biden's approach to the region, where China remains to be the top trading partner for many of the Indo-Pacific nations.