The two-day G20 summit has kicked off in Australia's Brisbane as world leaders are gearing up to discuss tensions between the Western world and Russia.

Though the key focus of the conference, in which leaders of the US, Britain, China, Russia, and India are set to participate, will be to boost growth, talks are likely to be dominated by the growing tension in West-Russia, which is at its highest since the Cold War era.

Hinting about an imminent unfriendly reception for Russian President Vladimir Putin at the summit over Moscow's increasing military activities, Prime Minister David Cameron said in a news conference prior to the formal conference: "It is a large state bullying a smaller state in Europe, and we have seen the consequences of that in the past."

The British prime minister said Russia's recent actions involving aerial confrontation are "unacceptable".

In his opening remarks at the summit, Australian Prime Minister Tony Abbott said: "Obviously I would like this discussion to focus on the politics of economic reform. In the end, though, this is your retreat, it is open to any of you to raise any subject you wish."

Topics including the handling of Ebola outbreak and climate change are also likely to feature prominently in the talks.

Meanwhile, US President Barack Obama is using his visit to reiterate Washington's interests in Asia-Pacific in what has been seen as sending strong signals to China amid growing territorial tensions.

Renewing the US's Asia-Pacific "pivot" commitment to Washington's allies in the region, the American president in his thinly-veiled remarks said: "America will continue to stand up for our interests and principles including our unwavering support for fundamental human rights of all people. We do not benefit from a relationship with China or any other country in which we put our values and our ideals aside."