Former Ukraine president Viktor Yanukovych, ousted by pro-Western protests, has filed a suit with EU's top court against sanctions Brussels has imposed on him and two sons.

The European Court of Justice lists the Yanukovych suit along with cases made by several other prominent figures in the crisis, which was sparked when the former president ditched an EU Association Accord under intense pressure from Russia in November and eventually led to his ouster and the installment of a pro-Western team in Kiev.

Ukrainian troops claimed fresh gains Monday around one of the main remaining separatist strongholds as Moscow reportedly weighed up "targeted" cross-border strikes following the alleged deadly shelling of a Russian town.  

Ukraine's Western-backed President Petro Poroshenko said government forces had managed to break through a blockade by pro-Moscow rebels to reach soldiers camped out at the strategic airport in the insurgent-held bastion of Lugansk. 

Russian President Vladimir Putin and German Chancellor Angela Merkel agreed in talks in Brazil on Sunday that the situation in Ukraine, where Kiev is continuing an offensive against pro-Russian separatists in the east, is "deteriorating," the Kremlin said.

"Putin and Merkel had a constructive, very thorough dialogue during which they discussed in detail possible options for resolving the situation in Ukraine," Kremlin spokesman Dmitri Peskov told the Russian news agency Ria Novosti. "The two leaders agreed that unfortunately the situation is deteriorating."

Donetsk, one of the last bastions of pro-Russian rebels in eastern Ukraine, has become a ghost town as residents clog the roads and railway stations in a desperate scramble to escape advancing government troops.

The self-proclaimed prime minister of the Donetsk People's Republic, Oleksandr Borodai, claims more than 70,000 of the city's 900,000 inhabitants have already fled as Kiev's forces move within 20 kilometers (12 miles) of the city.

The Canadian government of Prime Minister Stephen Harper has added 14 individuals to a list of people facing economic sanctions and travel bans related to the Ukranian crisis.

"Russia's illegal occupation of the Crimean peninsula and provocative military activity remains a serious concern to Canada and the international community," Harper said in a statement Friday.

Panicked Ukrainians flooded highways and packed trains leading out of the main remaining rebel stronghold on Saturday fearing a reprisal assault by government forces after they lost 30 servicemen to defiant militants.

Separatists near the Russian border mowed down 19 troops in a hail of heavy rocket fire on Friday in a bloody reminder of their resolve to reverse the recent tide of government gains across the eastern rustbelt.

House raids, bugging devices, threats, violence and demeaning posters are just a few things Vladimir Putin's critics have faced while trying to run for city parliament in the Russian capital.

Two years after President Putin was elected for a historic third term - facing mass protests in Moscow where less than half of the population voted for him - the Kremlin strongman is riding high in the polls while the opposition is all but stamped out.

President Vladimir Putin visited Russia's Cold War ally Cuba on Friday, launching a tour that will see him cozy up to Latin America amid newly frayed relations with the West.

Putin's six-day trip will also take him to Argentina and Brazil, where he will take part in a summit of the BRICS group of emerging countries -- an agenda that neatly aligns with his push for a multi-polar world at a time when the Ukraine crisis has brought Moscow-Washington relations to a post-Cold War low.

Russia has circulated a proposal for a United Nations Security Council resolution on Ukraine that would demand a ceasefire between Kiev and pro-Russian insurgents, Moscow's ambassador said Friday.

Other elements of the measure would give a greater role to the Organization for Security and Cooperation in Europe, Vitaly Churkin told reporters.

Fugitive U.S. intelligence contractor Edward Snowden could have his request to extend his asylum in Russia agreed within a week, a senior migration service representative said Friday.

"Snowden's life is still in danger, so the Federal Migration Service has every basis to extend his status," the head of the service's public chamber, Vladimir Volokh, said Friday, quoted by the Interfax news agency.