Moscow said on Monday that U.S.-led military exercises in western Ukraine that began this week may have "explosive" consequences and threaten to derail the peace process in the separatist east.

"The military drills involving NATO members and Ukraine's army that started in Lviv region under U.S. command are a clear demonstration of NATO's provocative policy to unequivocally support the policies of current Kiev authorities in eastern Ukraine," the foreign ministry said in a statement.

The nomination of a Russian politician to a top post in Odessa has caused a flurry of controversy in the tense political atmosphere of the violent Ukraine conflict.

Maria Gaidar, daughter of former Russian prime minister Yegor Gaidar, was nominated Friday as deputy to pro-Western former Georgian president Mikheil Saakashvili -- who was recently named governor of the southwest Ukraine region of Odessa. 

Two civilians and a soldier have been killed in the latest fighting in eastern Ukraine, pro-Russian rebels and the government said Sunday, with Kiev warning of a "deteriorating" situation in the rebel-held city of Donetsk.

A man was killed during shelling Saturday night in Donetsk and a female doctor was injured when a shell hit the nearby N23 hospital, rebel authorities told AFP. Another man was injured in the eastern rebel-controlled suburb of Makiivka.

Russia on Friday dismissed constitutional amendments proposed by Kiev to decentralize Ukraine as part of the peace process as merely an "imitation" of compliance.

Ukraine's parliament on Thursday voted in favor of sending to the Constitutional Court a package of reforms that would grant greater autonomy to the war-ravaged separatist east.

Ukraine outraged Russia on Friday by expelling Moscow's top envoy to a vital Black Sea region now governed by the pro-Western former president of Georgia.

The State Security Service of Ukraine (SBU) said Kiev had declared Moscow's consulate general in Odessa "persona non grata" for conducting unnamed activities "incompatible" with his diplomatic work.

Relatives of victims of flight MH17 that was shot down over Ukraine a year ago joined emotional memorials on Friday as calls mounted for a U.N.-backed tribunal to prosecute those responsible for the tragedy.

All 298 passengers and crew -- the majority Dutch -- died on July 17 last year when the Malaysia Airlines Boeing 777, on a flight from Amsterdam to Kuala Lumpur, was downed over rebel-held east Ukraine during heavy fighting between Kiev's armed forces and pro-Russian separatists.

Russian President Vladimir Putin said Thursday that establishing an international tribunal to prosecute those behind the downing of Malaysia Airlines flight MH17 over rebel-held east Ukraine would be counterproductive.

He made his comments in a telephone conversation with Prime Minister Mark Rutte of the Netherlands, whose citizens made up the majority of the 298 people killed in the July 17 disaster last year.

Ukraine lost eight soldiers Wednesday in a dramatic spike in fighting with pro-Russian gunmen that further imperiled a truce Washington's top European envoy is desperately trying to salvage in Kiev.

Separatist rebels also reported the death of two fighters and a civilian in shelling across the eastern industrial heartland of the former Soviet nation that took a decisive tilt toward the West more than a year ago.

Russian investigators said Monday that a Ukrainian pilot controversially detained in Moscow faces up to 25 years in prison for her alleged involvement in the killing of two Russian journalists.

Nadezhda Savchenko, Ukraine's first female military pilot, has been accused of abetting the deaths of Russian journalists Igor Kornelyuk and Anton Voloshin, who were killed by mortar fire in eastern Ukraine last summer.

President Petro Poroshenko confronted a fresh crisis Monday as a deadly standoff continued between interior ministry units and armed Ukrainian ultra-nationalists in a western enclave near Hungary.

The EU-backed leader planned to convene his "military cabinet" of top generals Monday to try and diffuse tensions between two forces vital to his bid to stamp out a separatist insurgency 1,000 kilometers (more than 600 miles) away in eastern Ukraine.