A German embassy worker has been expelled from Moscow in what Berlin sees as a "retaliatory" move, a German foreign ministry source said Saturday.

"An employee of the German embassy in Moscow has left the country because of a retaliatory measure by the Russian authorities," the source told AFP, confirming a report by the German newsweekly Der Spiegel.

Russia on Friday warned France of "serious" consequences unless Paris delivers by the end of this month a Mistral-class assault warship whose handover has been delayed by concerns over Moscow's role in the Ukraine crisis, a report said.

"We are preparing for different scenarios. We are waiting until the end of the month, then we will lodge serious claims," the state news agency RIA Novosti quoted an anonymous high-ranking Moscow source as saying.

Tens of thousands of supporters of President Vladimir Putin and a smaller group of ultra-nationalists marched through Moscow on Tuesday to mark Russia's Unity Day.

The huge, highly organized rally of Putin backers through the center of the capital showcased the Kremlin's patriotic agenda at a time of growing international tension over the war in neighboring Ukraine.

Russia endorsed a crushing victory for Ukraine's pro-Moscow rebel leadership after controversial polls on Sunday that the EU slammed as a "new obstacle" for peace in the country's strife-torn east.

The swift acceptance of the results by Russia looked certain to spark a diplomatic firestorm, with a fresh round of Western sanctions against the Kremlin now increasingly on the cards.

President Vladimir Putin's spokesman on Wednesday ridiculed U.S. media reports that the Russian strongman may be suffering from cancer, saying he was fine and that journalists should "shut their trap".

Dmitry Peskov blasted those behind speculation that the 62-year-old Putin -- who has long cultivated an action-man image -- was in ill health.

Russia has detained four Moscow airport employees over a plane crash which killed the head of French oil giant Total, whose private jet hit a snowplough on takeoff, investigators said Thursday.

Those detained include the air traffic controller in charge of directing the doomed plane at Vnukovo airport, her supervisor, the head of air traffic controllers and the chief of runway cleaning, Russia's investigative committee said in a statement. 

Thousands of Russians on Sunday marched through Moscow to protest against the Kremlin's involvement in the Ukraine crisis, in the country's first major anti-war rally since fighting erupted in April.

A huge column of protesters moved through the heart of the capital to condemn Moscow's role in a conflict that has claimed nearly 3,000 lives and pitted Russians against Ukrainians.

Ukrainian lawmakers on Tuesday adopted legislation granting limited self-rule to parts of the pro-Russian east as they prepared to ratify a landmark EU pact at the heart of the country's deadliest crisis since independence.

Russian Ambassador Alexander Zasypkin revealed that Moscow decided to provide Lebanon with military assistance promised four years ago after it was encouraged by the Saudi grant to Lebanon.

“The Saudi grant was an incentive to revive the Russian grant and put it on the move,” Zasypkin told An Nahar newspaper in an interview published on Tuesday.

U.S. President Barack Obama said Thursday that the United States would intensify sanctions in the defense, finance and energy sectors to punish Russia over its "illegal actions" in Ukraine, as the European Union said it could lift a new set of sanctions if a Ukraine ceasefire holds.

Obama said in a statement the move would worsen the Kremlin's deepening political and economic isolation.