Russian foreign minister Sergei Lavrov has accused Ukraine of violating an agreement reached in Geneva last week aimed at averting a wider conflict.
"Steps are being taken - above all by those who seized power in Kiev - not only that do not fulfil, but that crudely violate the Geneva agreement," he said.
Lavrov also told a news conference that a deadly gunfight early on Sunday near a Ukrainian city controlled by pro-Russian separatists showed Kiev did not want to control "extremists".
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In an exclusive interview with NBC News, the Ukrainian Prime Minister warns of the dangers of unchecked Russian expansion and aggression.