Russian Foreign Minister Sergei Lavrov is to meet Chinese President Xi Jinping in Beijing next week and will discuss with him the situation in Ukraine, the Russian foreign ministry said Sunday.

Lavrov will visit China on Tuesday, ahead of four-way talks between diplomats from the European Union, United States, Ukraine and Russia planned in Geneva on Thursday. Those talks are now in doubt amid violent clashes between supporters of Kiev and pro-Russian protesters in eastern Ukraine.

The Communist Party won a surprise victory against President Vladimir Putin's ruling party in a mayoral race in Russia's third largest city of Novosibirsk, election officials said on Monday.

Communist lawmaker Anatoly Lokot won 43.75 percent of the vote against the acting mayor Vladimir Znatkov from the ruling United Russia party, who took 39.57 percent, the Siberian city's electoral commission said.

Congress easily passed a U.S. aid package for Ukraine on Tuesday that includes sanctions against Russia for annexing Crimea, in U.S. lawmakers' first binding response to the crisis.

The House of Representatives voted 378 to 34 to approve the bill, which the Senate green-lighted last week, meaning the bill, including $1 billion in loan guarantees to Ukraine, now goes to President Barack Obama for his signature.

The United States is giving ex-Soviet Moldova $10 million to strengthen security on its border with Ukraine, Washington's top diplomat in Europe Victoria Nuland said Sunday.

Part of Moldova's eastern border with Ukraine is occupied by the breakaway Russian-speaking region of Transdniestr.

Ukraine's defense minister said Sunday that Russia had agreed to temporarily lift its blockade of Ukraine's military bases in Crimea in order to ease tensions surrounding the peninsula's secession referendum, as Moscow said it would respect the “choice” of the flashpoint region's residents.

"Agreements have already been reached between our commanders... on there being no attempts to blockade our military installations until March 21," Interfax quoted Defense Minister Igor Tenyukh as saying.

Moscow stocks plunged to a four-year low Friday as jittery investors dumped their holdings ahead of a referendum in Crimea over its bid to break away from Ukraine and join Russia.

The capital's two main indices MICEX and RTS opened down, but losses accelerated to more than 5.0 percent by midday before recovering to 4.37 percent and 4.82 percent, respectively.

Ukrainian police on Thursday arrested scores of pro-Moscow militants including a self-declared "people's governor" in the eastern city of Donetsk after re-taking regional government headquarters.

Officers from Ukraine's security services notified Pavel Gubarev of the arrest order against him at his home in Donetsk.

Moscow's stock markets opened more than three percent higher on Tuesday after plunging over 10 percent the day before in reaction to Russia's military intervention into Ukraine.

By around 0620 GMT, Moscow's MICEX bourse had risen by 3.20 percent while the other main Russian market, the RTS, had risen by 3.30 percent. In the opening minutes they had risen by more than four percent.

Russia had little option other than to offer sanctuary to deposed Ukrainian president Viktor Yanukovych, even if there is little love lost between him and President Vladimir Putin, analysts said Thursday.

Yanukovych is now widely believed to be in Russia after he released a statement saying he had asked Moscow to ensure his security and sources in the country said his wish had been satisfied on "Russian territory."

Russian police detained hundreds of protesters Monday outside a court that sentenced seven activists to prison terms of up to four years for demonstrations against Vladimir Putin's third presidential inauguration.

The Moscow court sentenced the seven defendants to penal colony terms of between two and a half and four years for what the judge ruled to be "mass riots" during the 2012 demonstrations, a high-profile case that has become a symbol of the harsh crackdown on opposition protests since Putin returned to the Kremlin.