French President Francois Hollande said Sunday he would not be pressured into delivering two warships to Russia, after delaying their handover due to the Ukraine crisis.

Sanctions-hit Russia risks deeper isolation from the global community unless it takes a different path on Ukraine, U.S. President Barack Obama said Sunday at the end of a stormy G20 summit.

Obama said if President Vladimir Putin "continues down the path that he is on, violating international law, providing heavy arms to the separatists in Ukraine.... then the isolation that Russia is currently experiencing will continue".

Russian President Vladimir Putin on Sunday shrugged off a hail of Western fire over the Ukraine crisis as G20 leaders wrapped up an annual summit focused on a drive to overhaul the global economy. 

At the summit in Brisbane, Putin broke protocol by delivering remarks to the media before the host leader's closing news conference, and then flew out a little early. 

Iran and six world powers begin a final round of talks in Vienna on Tuesday aiming to overcome significant remaining differences and agree a historic nuclear deal by a November 24 deadline.

"There's still a big gap. We may not be able to get there," U.S. President Barack Obama warned last Sunday.

A German embassy worker has been expelled from Moscow in what Berlin sees as a "retaliatory" move, a German foreign ministry source said Saturday.

"An employee of the German embassy in Moscow has left the country because of a retaliatory measure by the Russian authorities," the source told AFP, confirming a report by the German newsweekly Der Spiegel.

Despite living in a tiny cellar in Donetsk for more than three months, Sergei is not complaining about the frequent shelling or lack of running water. Instead, he saves his fury for his own country -- Ukraine.

"It's the Ukrainian army that has done all this damage," the 56-year-old former miner rages, standing in front of the dusty mattress he sleeps on as his wife watches with pursed lips.

Vladimir Putin intends to cut short his attendance at the Group of 20 summit in Brisbane on Sunday, a Russian source said as the strongman faces intense pressure from the West over Ukraine.

"The program of the second day (for Putin) is changing, it's being cut short," a source in the Russian delegation told AFP on condition of anonymity.

Russian President Vladimir Putin on Saturday called on French President Francois Hollande to "minimize the risks" between their countries after months of growing tensions.

"There are a lot of turbulent moments in world affairs and not on all issues do our positions converge," Putin said on the margins of the G20 summit.

Secret "Russian subs" off Sweden, tit-for-tat sanctions, NATO fighters scrambling to intercept Russian warplanes: relations between the West and Moscow over Ukraine have sparked incidents reminiscent of the Cold War that terrified the world for decades.

Even Cold War doyen Mikhail Gorbachev used the highly symbolic 25th anniversary of the fall of the Berlin Wall to warn the world was "on the brink of a new Cold War", adding that "some are even saying that it has already begun".

The United States has reportedly questioned Mustaqbal Movement leader MP Saad Hariri's decision to “diversify” the number of countries from which to obtain weapons as part of the Saudi military grant to the army, said As Safir newspaper on Saturday.

Widely informed sources told daily that the U.S. filed an official complaint to the Lebanese government, the army command in particular, for attempting to strike a deal with Russia on supplying the army with used T-72 tanks.