Speaking at a news conference on Monday, Lavrov said that "steps are being taken - above all by those who seized power in Kyiv - not only that do not fulfill, but that crudely violate the Geneva agreement."

Last Thursday, four-way talks in Geneva between Ukraine, Russia, the US and the EU had yielded an agreement detailing concrete measures to defuse tensions in eastern Ukraine.

He also criticized Ukraine's interim government for not clearing what he called "illegal" protesters from Maidan Square in the capital Kyiv. "This is absolutely unacceptable," he said.

Lavrov told reporters that Sunday's deadly shootout near the eastern Ukrainian flashpoint of Slovyansk, was a crime and showed that Kyiv did not want to control who he labeled "extremists."

"The authorities are doing nothing, not even lifting a finger, to address the causes behind this deep internal crisis in Ukraine," he said.

Russia's foreign ministry on Sunday blamed Ukraine's ultra-right wing faction, the Right Sector, saying that it was "outraged" at the attack on "innocent civilians." However, Right Sector spokesperson Artyom Skoropatskiy denied involvement and sided with Kyiv's assertions that Russian provocateurs had staged the attack.

Biden due in Kyiv

Lavrov's broadside against Ukraine came ahead of a visit there by US Vice President Joe Biden, who is due to hold talks with Ukraine's acting Prime Minister Arseniy Yatsenyuk, among others.

The US and other Western nations, including Germany, have urged Moscow to do what it can do defuse tensions in eastern Ukraine, by using its alleged influence over pro-Russian separatists in the region. Moscow insists it has nothing to do with the forces operating there.

Lavrov also slammed the US for threatening more sanctions if they fail to uphold the terms of the Geneva deal. "Before giving us ultimatums, demanding that we fulfill demands within two or three days with the threat of sanctions, we would urgently call on our American partners to fully accept responsibility for those who they brought to power," he said in a thinly veiled attack on the interim government in Kyiv.

ng/hc (Reuters, AP, dpa)