Syria's opposition on Friday urged President Bashar Assad's government to speak out on whether it will take part in an international peace conference, after Russia claimed the regime had agreed "in principle" to attend.

"We would like to hear that statement from the Assad government. This has been related to us through the Russians, I have no idea why the Syrians are silent," Louay Safi, spokesman for the National Coalition, told Agence France Presse at a meeting of the main Syrian opposition group in Istanbul.

A massive undersea earthquake Friday in Russia's Far East prompted a tsunami warning and unleashed tremors across Russia including in Moscow around 7,000 kilometers away, but caused no casualties or damage.

The U.S. Geological Survey (USGS) estimated the quake at 8.3 magnitude and placed its epicenter in the Sea of Okhotsk off the shore of the Kamchatka Peninsula at a depth of more than 600 kilometers (370 miles).

Russia has ordered the urgent evacuation of the 16-strong crew of a drifting Arctic research station after the ice floe that hosts the floating laboratory began to disintegrate, officials said Thursday.

Natural Resources and Ecology Minister Sergei Donskoi set a three-day deadline to draft a plan to evacuate the North Pole-40 floating research station.

Syria's main opposition group opened key talks Thursday in Istanbul to debate whether to negotiate with the regime on ending the bloody two-year civil war, as proposed by the U.S. and Russia.

During their three-day meeting, the Syrian National Coalition -- which is under fire from both its backers abroad and rebels on the ground -- is also expected to choose a new president, discuss expansion to include new members and decide the fate of an interim rebel government, opposition members told AFP.

Russian Foreign Minister Sergei Lavrov on Wednesday hailed the Syrian regime's "constructive reaction" to a proposed peace conference on ending the bloodshed in the war-torn country, as he welcomed Syrian Deputy Foreign Minister Faisal Muqdad in Moscow.

"We value the constructive reaction by the Syrian leadership to the offer" of holding the international event, Lavrov said, adding that he hoped to "discuss specific details" during Muqdad's visit.

Russian opposition leader Alexei Navalny on Wednesday received a boost in his controversial trial for embezzlement when a witness for the prosecution testified in support of the Kremlin critic.

The testimony by Kirov region governor Nikita Belykh was the latest to undermine the prosecution case, which the opposition has denounced as a set-up ordered by the Kremlin to end Navalny's political career.

Russia's federal guard service launched an investigation after photos appeared in the media of a disgraced former employee posing behind Vladimir Putin's desk in the Kremlin, an official said Tuesday.

Pictures of the man, named Alexei Ustimchuk, sitting diminutively behind the giant desk in Putin's Kremlin office, spread through the internet as people ridiculed the lack of security that permitted a simple employee such access.

Russia was Tuesday set to question the sole survivor of a deadly police raid outside Moscow that authorities said had prevented a major attack in the capital.

The operation in the Moscow region town of Orekhovo-Zuyevo took place shortly after twin car bombs killed four and injured more than 40 in the restive Dagestan region.

A 6.0-magnitude earthquake struck Russia's Kamchatka Peninsula early Tuesday, followed by a series of strong after-shocks, the US Geological Survey reported.

The first quake struck at a depth of 33 kilometers (20 miles) at 0155 GMT, 136 kilometers east-southeast of the Russian city of Petropavlovsk-Kamchatsky, the USGS reported.

Russian security services said Monday they had foiled a terror attack on Moscow, killing two of the plotters and arresting another.

"Our forceful actions prevented an attempted act of terror in the capital," the National Anti-Terror Committee said in a statement.