US Secretary of State John Kerry has attacked Russia for its deception and distraction over the Ukraine crisis, warning that the window for Moscow to change course was closing.

In an impromptu briefing, held on Thursday, he told reporters that while Ukraine was working in good faith to restore peace and reduce tension, Russia was putting its faith in "destruction, deception and destabilisation".

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"Let’s get real, the Geneva Agreement is not open to interpretation. It is not vague. It is not optional," he said, referring to a pact signed seven days ago between Russia, the US, the European Union and Ukraine to defuse the crisis and work towards constitutional reform.

Ukraine's interim leadership had from "day one" kept their word after agreeing to the Geneva deal but Kerry accused Russia of a "full-throated effort to actively sabotage the democratic process" in Ukraine. "Nobody should doubt Russia's hand in this," he said.

"Let me be clear, if Russia continues in this direction, it will not just be a grave mistake but an expensive mistake. The window to change course is closing."

Kerry said that $70bn of capital had already "fled" Russia in the first quarter of 2014 and that growth estimates had been reduced by two to three per cent.

He reiterated the sentiments of President Barack Obama, who earlier in the week said Russia was failing to abide by the Geneva accord, and that new sanctions against Moscow were being "teed up".

"So far we have seen them not abide by the spirit or the letter of the agreement in Geneva," Obama said. If that continued, he said, "there will be further consequences and we will ramp up further sanctions."

Source: Al Jazeera and agencies