Ukraine handed foreigners -- including a U.S. citizen -- top posts in a new reformist government on Tuesday aimed at rooting out endemic corruption amid a new push for a general ceasefire in the separatist east.

President Petro Poroshenko told a marathon parliament hearing that Ukraine had to learn from "foreign experience" as it tries to climb out of bankruptcy that many blame on decades of political gridlock and graft.

The Russian economy ministry on Tuesday slashed its economic forecast for 2015, announcing a contraction of 0.8 percent due to the pressure of Western sanctions over the Ukraine crisis combined with falling oil prices.

The ministry cut its previous outlook of 1.2 percent growth by two percentage points, referring to worsening economic indicators and a "more conservative" assumption that Western sanctions will remain through 2015.

Ukraine and pro-Russian separatists agreed Tuesday to a truce at Donetsk airport -- ground zero in a war that has killed more than 4,000 people -- as well as across a wider swathe of rebel-held territory.

"Today, we reached an agreement to halt fire at 6:00 pm Moscow time (1500 GMT) around Donetsk airport," the self-declared Donetsk People's Republic co-leader Andrei Purgin told reporters.

NATO foreign ministers met in Brussels Tuesday aiming to plot a new course after a "year of aggression" from Ukraine to the Middle East and the end of the alliance's combat mission in Afghanistan.

New chief Jens Stoltenberg said as he arrived that U.S. Secretary of State John Kerry and other ministers from the 28-nation group would discuss how to "drive our alliance forward in a changing world."

Russia lashed out at NATO on Monday, saying the alliance risked "destabilizing" Europe with military drills linked to a spike in tensions over the Ukraine crisis.

Russia's deputy foreign minister Alexei Meshkov said the U.S.-led military alliance was "trying to destabilize the world's most stable region".

New European Council chief Donald Tusk and U.S. President Barack Obama urged Russia on Monday to pull back from eastern Ukraine, in a telephone call on Tusk's first day in office, the EU said.

"We shared our concerns over the crisis in Ukraine and agreed on how important it is for Russia to withdraw from eastern Ukraine, to stop supplying troops and equipment, to allow effective control of the border," former Polish premier Tusk said in a statement released by Brussels.

President Vladimir Putin on Monday unexpectedly announced Russia was shelving the multi-billion dollar South Stream pipeline project to deliver Russian gas to the Europe, blaming the EU for throwing obstacles in its path.

Putin revealed on a visit to Ankara that Russia was drawing the curtain on what for half-a-decade has been one of the Kremlin's flagship projects, saying Turkey in the future could play an important role as a gas hub.

The first troops of a high-speed NATO reaction force designed to meet the sort of crisis highlighted by Russia's Ukraine intervention should be ready early next year, officials said Monday.

NATO leaders agreed at a summit in September that the 28-member military alliance needed a new "spearhead" force which could be deployed within days to cope with emerging threats.

At least three Ukrainian soldiers have been killed and 14 injured in the past 24 hours as fighting intensifies for control of Donetsk airport, a military spokesman said Monday.

Fierce battles resumed in the past three days around the ruins of the airport in eastern Ukraine, said spokesman Andriy Lysenko.

The beleaguered ruble hit new record lows on Monday after oil prices sank further amid spreading worries about Russia's economy.

The Russian currency fell for a third day in a row, slumping to over 52 rubles against the dollar and 65 rubles against the euro in afternoon trading on the Moscow Exchange.