G20 heads of state and government clubbed together Sunday to rebuke Russian President Vladimir Putin over his alleged support of separatist rebels in eastern Ukraine.

At the group communique, several Western leaders warned Putin that Moscow risked more economic sanctions if it did not withdraw troops from the country.

The Kremlin has continually denied arming pro-Russian rebels, but as temperatures soared to record highs in host city Brisbane, diplomacy towards the increasingly isolated Russian president evaporated.

In the lead up to the summit, Britain’s Premier David Cameron, speaking to the Australian parliament, had referred to Moscow’s actions as “unacceptable."

“It is a large state bullying a smaller state in Europe. We’ve seen the consequences of that in the past and we should learn the lessons of history and make sure we don’t let it happen again,” Cameron said.

Putin and Canadian Prime Minister Stephen Harper had a particularly tense exchange on Saturday morning. Putin extended his hand to Harper and received in return a frosty reception and a blunt message.

According to the Canadian leader’s spokesperson, Harper told Putin: “I guess I'll shake your hand but I have only one thing to say to you: You need to get out of Ukraine.”

Much of the summit dwelt on Putin's position in the country.

During the weekend, Australian Foreign Minister Julie Bishop told a local national television channel: “I believe President Putin has been under quite some pressure at the G20 by a number of leaders, including Australia, about the downing of MH17.

“But also their aggressive attitude towards Ukraine, the obvious breach of territorial sovereignty and the fact that Russia refuses to acknowledge the role and the influence it has over the conflict in Ukraine.

"We should be encouraging Russia to be a responsible international citizen. If it wants to be taken seriously and if it wants to maintain its status as a significant economy, a significant nation, then it has to abide by international norms."

United States President Barack Obama, Australian Prime Minister Tony Abbott and Japan’s Prime Minister Shinzo Abe are demanding justice for those who died when a missile suspected to have been fired by Russian-backed rebels shot down Malaysian Airline MH17 over eastern Ukraine in July, leading to the loss of 298 lives - among them 38 Australian citizens and residents.

The three leaders said they oppose “Russia's purported annexation of Crimea and its actions to destabilize eastern Ukraine,” and are committed to “bringing to justice those responsible for the downing of Flight MH17.”

In his post summit press conference, Obama told reporters Putin was “violating international law, providing heavy arms to the separatists in Ukraine” and violating the Minsk agreement.

He said the “economic isolation” of Russia would continue unless Putin changed course.

Putin was constantly hammered over Ukraine and left the summit early. But while on Thursday he had told Russia’s TASS state news agency that sanctions against Russia violated the G20’s principles and were “harmful,” he praised the weekend’s discussions. His departing remarks were that the weekend was “constructive”.

His justification for leaving before the formal end of the two-day summit was that he needed sleep.

Russian news agency RIA Novosti reported Putin as saying: “It will take nine hours to fly to Vladivostok and another eight hours to get Moscow. I need four hours sleep before I get back to work on Monday. We have completed our business.”

Anadolu Agency