A showdown between Western leaders and Russian President Vladimir Putin is likely at the G20 summit in Australia starting today, following fresh reports of Russian troops pouring into eastern Ukraine.

British Prime Minister David Cameron blasted Russia’s actions as unacceptable yesterday, warning that they could draw greater sanctions from the United States and the European Union.

“If Russia takes a positive approach towards Ukraine’s freedom and responsibility, we could see those sanctions removed; if Russia continues to make matters worse then we could see those sanctions increased, it’s as simple as that,” Cameron told reporters in Canberra.

Russia denies sending troops and tanks into Ukraine.

Vladimir Putin walks down from his aeroplane after arriving at the G20 Terminal in Brisbane, Australia, yesterday. Photo: Reuters

If Russia makes matters worse then sanctions may rise

In an interview with Russian state news agency Tass, Putin said the sanctions harmed Russia, but also the global economy.

He said he would not bring up the issue at G20 as “it’ll make no sense”. He was not asked about Ukraine in the interview.

The G20 leaders summit in Brisbane is focused on boosting world growth, fireproofing the global banking system and closing tax loopholes for giant multinationals.

But with much of the economic agenda agreed and a climate change deal signed last week in Beijing between the United States and China, security concerns are moving to centre-stage.

Ukraine has not been a top focus during a pair of summits in Asia this week, US Deputy National Security Adviser Ben Rhodes said, although President Barack Obama did raise it briefly with Putin when both attended the Asia Pacific Economic Cooperation forum in China.

Obama arrives in Brisbane today and will be discussing his frustration over Ukraine with a key bloc including German Chancellor Angela Merkel, French President Francois Hollande and Cameron.

There had been some calls in Australia to block Putin from attending the summit given Russia’s actions in Ukraine and the downing of Malaysia Airlines Flight MH17 by Russian-backed rebels, but the overwhelming consensus was against it.

News reports that a convoy of Russian warships had arrived earlier this week in international waters north of Brisbane also created a flutter.

Australian Prime Minister Tony Abbott said it was unusual but not unprecedented for the Russian navy to be so far south.