Russia, US trade jabs over Ukraine deal

Moscow and Washington have each called for more action from the other to save a troubled deal aimed at easing the crisis between Ukraine's new Western-backed government and pro-Russian separatists in the east.

As US Vice President Joe Biden began a two-day visit to Kiev - a pointed show of American backing for Ukraine's new leaders - Washington and Moscow each put a radically different spin on a crunch telephone call between their diplomatic chiefs on reviving the accord reached last week in Geneva.

Under the deal, signed by Ukraine, Russia, the United States and the European Union, pro-Kremlin rebels holding a string of eastern towns were supposed to disarm and give up the buildings they have seized.

The accord was meant to lower the heat on the worst confrontation between Washington and Moscow since the Cold War, but each side has accused the other of violating it.

US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov each urged the other to put pressure on his side in the crisis - in Kerry's case, on the Ukrainian government, which Moscow accused of "grossly breaching" the Geneva deal; in Lavrov's, on the separatist rebels, which Washington sees as backed by Russia.

Kerry told Lavrov that "concrete steps" to defuse the crisis should include "publicly calling on separatists to vacate illegal buildings and checkpoints, accept amnesty and address their grievances politically", said State Department spokeswoman Jen Psaki.

In Moscow, the Russian foreign ministry said Lavrov had asked Kerry to "pressure Kiev to stop hotheads from provoking a bloody conflict and to encourage the Ukrainian authorities to strictly fulfil their obligations", the Russian foreign ministry said.

Lavrov also accused Ukraine's government of an "inability and unwillingness" to rein in Pravy Sektor ("Right Sector"), an ultra-nationalist group the separatists blamed for an attack Sunday on one of their checkpoints in the flashpoint town of Slavyansk.

The shootout, started by unidentified attackers, broke a brief Easter truce and killed at least two separatist rebels.

US President Barack Obama has threatened more sanctions on Moscow if the Geneva accord is not implemented soon, beyond those already imposed by the United States and the European Union.

But Lavrov said it was the Ukrainian government that was violating the deal and told reporters in Moscow that sanctions would fail.

"Attempts to isolate Russia have absolutely no future because isolating Russia from the rest of the world is impossible," he said.

His country, he said, was "a great power, independent, and it knows what it wants".

Russia, which annexed Ukraine's Crimea peninsula last month after sending in troops, has massed a military force estimated at 40,000 soldiers on Ukraine's eastern border.

The United States and NATO have responded by boosting their own forces in eastern Europe. A report in The Washington Post said the United States was poised to send ground troops to neighbouring Poland.