Western leaders on Tuesday called for a "strong reaction" from the international community if a major violation of a truce in Ukraine occurs, the French presidency said after video conference talks.

The leaders of the United States, France, Germany, Britain and Italy as well as EU head Donald Tusk held video talks on the Ukraine conflict on Tuesday.

Exiled Russian former tycoon Mikhail Khodorkovsky warned on Friday that Vladimir Putin's policies in the Ukraine conflict will bring Russia to ruin, much as the Afghan war helped bankrupt the Soviet Union.

A year after annexing Crimea in Ukraine, Russia finds itself isolated and on a path to self-destruction, said Khodorkovsky, one of Putin's most outspoken critics, who spent a decade in prison on what he said were politically motivated charges.

A Ukrainian airforce pilot, who has been on hunger strike in a Russian prison for 77 days, "could die within days," a member of the Kremlin's human rights council said Friday.

Nadia Savchenko, a 33-year-old helicopter navigator, who has been charged with involvement in the deaths of two Russian reporters in a mortar attack in east Ukraine, has been held in a Moscow jail for nearly nine months.

Cyprus played down on Thursday an agreement granting Russian warships access to its ports and denied there was any request from Moscow to open a base on the island.

The heavily indebted eurozone member has close investment and tourism ties with Russia and has repeatedly expressed misgivings about EU sanctions against Moscow.

A Russian court has jailed top Kremlin critic Alexei Navalny for two weeks in a move that prevents the charismatic leader from attending a massive opposition protest planned for March 1.

The Moscow Presnensky court ruled that Navalny, who has a string of probes against him and was given a suspended prison sentence in December, organised an illegal gathering in the capital's subway by handing out flyers advertising the March 1 protest.

Russia could inflict the tactics it is accused of using to destabilize Ukraine on Baltic members of NATO, Britain's defense minister warned in comments to British newspapers on Wednesday.

Michael Fallon said that NATO must be prepared for Russian aggression in any form, and warned of a "real and present danger" to Baltic members of NATO -- eurozone members Estonia, Latvia and Lithuania.

The leaders of Russia, Germany and Ukraine have agreed on "concrete measures" to allow OSCE observers to monitor the shaky ceasefire in Ukraine, Berlin announced on Tuesday.

The measures were agreed during a late Monday phone call between German Chancellor Angela Merkel and her Russian and Ukrainian counterparts, Vladimir Putin and Petro Poroshenko, the government spokesman said in a statement, without providing details of the agreed steps.

Hundreds of Hungarians took to the streets of Budapest on Monday to protest against Vladimir Putin, a day ahead of the Russian leader's visit to Budapest. 

According to an Agence France-Presse photographer, around 2,000 people marched between the capital's two main train depots, the Eastern and Western stations. 

Russia wanted an immediate ceasefire in Ukraine and the Sunday morning deadline was agreed in talks in Minsk under pressure from rebel leaders, President Vladimir Putin's spokesman was quoted as saying Friday.

Russia "supported an immediate ceasefire," Putin's spokesman Dmitry Peskov was quoted as saying by the Kommersant business daily. 

A new roadmap aimed at ending a 10-month war between Ukraine and pro-Moscow rebels was agreed in Belarus Thursday, but skepticism remained as leaders warned much needed to be done before peace was achieved.

After a marathon summit in the Belarussian capital Minsk, Russian President Vladimir Putin said he, Germany Chancellor Angela Merkel, French President Francois Hollande and Ukrainian President Petro Poroshenko had reached a ceasefire deal.