Russia's Foreign Ministry accused Ukraine's interim government on Tuesday of making "military preparations" in eastern Ukraine that could lead to "an outbreak of civil war."

Moscow appeared to be responding to a statement from Ukraine's Interior Minister Arsen Avakov that interim government security forces had blocked off the center of Kharkiv, including metro stations.

Avakov said about 70 "separatists" had been arrested in an "anti-terrorist operation."

The Internet television channel Hromadske said no shots were fired when special forces cleared the Kharkiv administration building.

'Crimea scenario,' says Kyiv

On Sunday, pro-Russian protestors had seized official buildings in three eastern Ukrainian cities - Kharkiv, Donetsk and Luhansk - prompting claims from Kyiv that Russia had orchestrated the occupations.

The protestors had demanded that referendums be held in eastern Ukraine, similar to the one that preceded Moscow's annexation of Ukraine's southern peninsula of Crimea last month.

On Monday, acting Ukrainian President Oleksander Turchinov in a televised speech said that Moscow was attempting to repeat the "Crimea scenario." He warned that "anti-terrorism measures" would follow.

Confrontations took place in Kharkiv on Monday night, between pro-Russian and pro-Kyiv protestors (pictured).

Lavrov denies destabilization

Russian Foreign Minister Sergei Lavrov on Monday denied that Moscow was destabilizing Ukraine and separately warned Kyiv against any use of force against pro-Russian demonstrators.

In a phone call with Lavrov on Monday, US Secretary of State John Kerry said that Washington was watching events in eastern Ukraine with great concern.

Kerry called on Russia to publicly disavow the activities of "saboteurs and provocateurs" in Ukraine, according to a US State Department message.

The State Department said that the pair had discussed plans to convene direct talks to defuse tensions over the next 10 days between Ukraine, Russia, the United States and the European Union.

Lavrov on Tuesday called for representatives from the Russian-speaking east and south of Ukraine to be included.

"Indeed we are ready to consider a multi-party format in which the Europeans, the United States, Russia and the Ukrainian sides are represented," Lavrov said.

"We are in favor of Ukraine's south and east being represented in such talks." He suggested that some of the pro-Russian candidates set to run in Ukraine's snap presidential elections in May might be suitable participants.

'Great concern,' says Germany

Germany government spokesman Steffen Seibert said Monday that Germany was worried by the actions of pro-Russian demonstrators in eastern Ukraine and called for stability in the region.

"We in the German government have been observing recent events in Donetsk and Kharkiv with a great deal of concern," he said.

Since Russia's annexation of Crimea, the US and the EU have imposed financial sanctions on some Russian officials. Western governments have hesitated to do more, given deliveries of Russian natural gas via pipelines across Ukraine.

ipj/msh (Reuters, AP, dpa)