Russian lawmakers at the Council of Europe's parliamentary assembly were stripped of their voting rights until the end of 2014 on Thursday over Moscow's annexation of Crimea.

The assembly at the Council, a body that has no legislative powers but promotes cooperation on human rights and democracy between European countries, gathers lawmakers from the parliaments of 47 member states, including 18 Russians and 12 Ukrainians.

Russia declined to provide the FBI with information about one of the Boston marathon bombing suspects two years before the attack, The New York Times reported Wednesday.

Three people were killed and about 260 wounded on April 15 last year when two bombs made of explosives-packed pressure cookers went off near the finish line of the marathon.

Russia successfully launched an unmanned cargo ship to the International Space Station on Wednesday evening after a spaceship carrying three astronauts experienced a technical glitch last month.

"At 19:35 Moscow time (15:35 GMT), the cargo ship separated from the third-stage booster rockets on schedule," the Russian space agency said in a statement on its website after the Progress M-23M ship blasted off from the Baikonur cosmodrome in Kazakhstan.

NATO denied Russian claims Wednesday that it was planning to deploy massive numbers of troops near the country's border.

"I totally dismiss claim by dep defense minister Antonov that NATO plans to deploy large military contingents close to Russia's borders," said NATO Deputy Secretary General Alexandre Vershbow on twitter.

Third countries should stay out of the debate over Ukraine's future constitution, Poland's prime minister said Wednesday, amid Russia's insistence on solving the crisis through federalization.

"Ukraine's future constitution should, in our opinion, be adopted by Ukrainians alone. And the shape of Ukraine's constitution should not be a topic of discussion for third countries," Prime Minister Donald Tusk told reporters.

Four-way talks between U.S. and EU diplomats, Russia and Ukraine to defuse Europe's worst security crisis in decades look set to be held Thursday next week in Vienna, an EU diplomat said.

"Intense talks are taking place ahead of the four-way negotiations April 17 in Vienna," said the source, speaking on condition of anonymity.

More than 50 people held "hostage" by pro-Russian militants who seized a security building in eastern Ukraine have been released, the state security service said on Wednesday.

Ukraine's SBU security agency said on Tuesday that separatists who had seized its regional headquarters in Lugansk on Sunday had mined the building and were holding 60 people "hostage."

Canada has ordered a Russian diplomat to leave the country, newspapers reported on Tuesday, but officials won't say why.

Lieutenant-Colonel Yury Bezler has been declared persona non grata and has been given two weeks to depart, after serving less than a year as assistant defense attache at the Russian embassy in Ottawa, said the Ottawa Citizen and others, citing unnamed sources.

Russia's security service confirmed Tuesday that Chechen rebel leader Doku Umarov, whose Caucasus Emirate group claimed responsibility for a string of deadly attacks, had been "neutralized" after insurgents announced his death last month.

The director of the FSB security service, Alexander Bortnikov, said that "the activities of the head of the Caucasus Emirate terrorist organization, Umarov, have been neutralized".

U.S. Secretary of State John Kerry warned Tuesday that Russia was sending agents into eastern Ukraine to "create chaos" the Kremlin could use as a pretext for more military intervention.

With tensions again on the boil in Ukraine, Kerry said he would meet next week with Russian Foreign Minister Sergei Lavrov as Washington seeks to tamp down the most serious East-West crisis since the Cold War.