Europe is on track to replenish its depleted natural gas storage network using almost no Russian pipeline supplies for the first time ever. But the region's plans to completely phase out Russian gas still look like a daunting challenge.

Russia's friends in Eastern Europe say EU plans to end all Russian gas and energy imports are tantamount to "economic suicide" and a threat to energy security.

European Council President António Costa has criticized the trip by Serbia's president to Russia’s Victory Day parade last week.

The Russian economy is in an increasingly precarious state as a result of a shift to a war mode and of Western sanctions over Moscow's invasion of Ukraine, a report by the Stockholm Institute of Transition Economics (SITE) said on Tuesday.

The EU is preparing new sanctions on Russia despite a potential meeting between Vladimir Putin and Volodymyr Zelenskyy on Thursday, three sources told CNBC.

The talks took place in the warring capitals of Moscow and Kyiv, from Washington and Riyadh, Saudi Arabia, to countries across Europe

The leader of a British-based Russian spy ring which prosecutors said carried out surveillance for the Kremlin was sentenced in a London court on Monday to nearly 11 years in jail, as his five team members were jailed for a total of about 40 years.

The Kremlin brushed off the threat of further sanctions, saying that “the language of ultimatums is unacceptable.”