A new round of talks aimed at finding a lasting solution to the Ukraine crisis will take place in Belarus on Friday, the ex-Soviet country's foreign ministry said.

"We confirm that such a meeting will happen" in the Belorussian capital Minsk, a foreign ministry spokesman told Agence France-Presse.

Kiev accused Moscow on Thursday of massing its troops in annexed Crimea on the Ukraine border, rattling nerves just as President Petro Poroshenko prepared to meet U.S. counterpart Barack Obama.

The apparent push north by about 4,000 troops in the Black Sea peninsula came despite Russia's declared backing of a peace overture by Kiev to try to end five months of conflict in the rebellious east.

Ukraine leaders have played a risky hand granting self-rule to the rebellious east of the country -- a strategy that may halt months of bloodletting but could well open the door to Russia, analysts said Wednesday.

Moscow has hailed the move by Ukrainian lawmakers Tuesday, although some defiant rebel leaders insist they will not be dictated to by a government they reject in Kiev.

Moscow on Wednesday praised Kiev's law on self-rule for the war-torn eastern Ukraine as a "step in the right direction" and expressed the hope the rebel-held regions would develop cross-border cooperation with Russia.

"In Russia this document is considered a step in the right direction which corresponds to the spirit of agreements cemented in the Geneva declaration between Russia, Ukraine, the United States and European Union from April 17 of this year, as well as the Berlin declaration from July 2 of this year," the foreign ministry said in a statement.

Fierce gunbattles erupted around the Ukrainian rebel stronghold of Donetsk on Wednesday, with two civilians killed just a day after lawmakers in Kiev held out an offer of self-rule to the pro-Russian separatists.

The United States on Tuesday welcomed Ukraine's ratification of a landmark EU pact and new laws granting self-rule to the east, urging Moscow to implement a ceasefire deal in return.

"We congratulate the people of Ukraine on making history today," State Department deputy spokeswoman Marie Harf said in a statement.

Zimbabwean's veteran president Robert Mugabe voiced his support for Russia on Tuesday, describing Western sanctions against Moscow as "illegal".

"If sanctions are to apply they must be approved by the U.N. and those that are being imposed on the Russian Federation have not," the 90-year-old said after meeting visiting foreign minister Sergei Lavrov.

Fighting in Ukraine has driven nearly 370,000 people to flee to neighboring countries, most of them to Russia, the U.N. said Tuesday.

"Some 366,866 people have fled to neighboring countries, the vast majority to Russia," Jens Laerke, spokesman for the U.N.'s humanitarian agency, told reporters in Geneva.

Russia's defense minister called on Tuesday for the deployment of reinforcements to Crimea and southern Russia, citing the worsening crisis in Ukraine and the buildup of foreign forces nearby.

Sergei Shoigu told a meeting of defense ministry top brass it was a "priority" to deploy a "full and self-reliant group of troops in the direction of Crimea", Russian news agencies reported.

A rebel leader on Tuesday dismissed Kiev giving the separatist east limited self-rule, saying Ukraine's eastern Donbass region was no longer part of the ex-Soviet country.

"Complete self-rule will be introduced in Donbass, this territory no longer has anything to do with Ukraine," Andrei Purgin, deputy prime minister of the self-proclaimed Donetsk People's Republic, told AFP.