Moscow and Washington are urging each other to exert influence on the two sides in the Ukraine crisis in the absence of any sign that last week’s Geneva accord is being implemented.

Pro-Russian separatists are still refusing to vacate buildings they’ve occupied in east Ukraine, and ultra-nationalists are being blamed for the weekend’s shootout at a separatist checkpoint.

In a web chat with a Russian radio station, the US State Department said more sanctions were being considered unless Moscow tells its allies in Ukraine back down, with even the Russian president now a possible target.

In a show of US support Vice-President Joe Biden has arrived in Kyiv where he’s expected to announce new technical support to the Ukrainian interim government to implement energy and economic reforms.

However Russia’s Foreign Minister Sergey Lavrov, has called for the US to restrain what he called the Kyiv “hotheads”.

“The Geneva agreement is not only not being implemented, but also steps are being taken – primarily by those who have seized power in Kyiv – that are crude violations of the agreements reached in Geneva. The authorities aren’t doing anything, they haven’t lifted a finger to eliminate the causes that are the basis for the deep crisis today in Ukraine.”

As the diplomatic exchanges continue, members of the OSCE – a European security body – has deployed mediators in Ukraine to explain the Geneva accord.