European shares and periphery euro zone bonds tumbled on Monday after the Greek parliament rejected the government's presidential candidate, setting the stage for an election that anti-bailout party Syriza could win.

Russia has agreed on a new deal to supply coal and electricity to Ukraine, which is struggling with a lack of raw fuel for power plants due to a separatist conflict in the industrial east, Russian officials said on Saturday.

Russia and US space relations may also be at risk as Vladimir Putin eyes new space station. NASA together with SpaceX, on other hand, prepares for its future crew missions to the International Space Station.

Ukraine's parliament gave preliminary approval on Thursday to a law that would simplify tax legislation and impose additional duties on imports, in an effort to raise revenue amid economic crisis.

Russia's rouble strengthened on Thursday as exporters sold foreign currency in response to government pressure and to meet tax payments, but trading volumes were thin as many Western markets were closed for the Christmas Day holidays.

Japanese stocks rallied and the dollar stood tall on Wednesday thanks to surprisingly robust U.S. economic growth, helping investors head into the Christmas holidays in a more relaxed mood after the global markets turbulence of the past two weeks.

U.S. president Barack Obama has rejected the charge that he has been outmaneuvered by Russian president Vladimir Putin, saying in a TV interview due for broadcast later on Sunday that Putin was presiding over "a huge economic contraction" due to the Ukraine crisis.

Saudi Arabia said on Sunday it would not cut output to prop up oil markets even if non-OPEC nations did so, in one of the toughest signals yet that the world's top petroleum exporter plans to ride out the market's biggest slump in years.

The United States has sought help from China, Japan, South Korea and Russia in combating cyber attacks such as the one Washington on Friday accused North Korea of carrying out against Sony Pictures, U.S. officials said.

China's trade minister proposed more use of China's currency in settling trade with Russia in the face of a falling rouble to ensure safe and reliable trade, Hong Kong broadcaster Phoenix TV reported on Saturday.