Acting foreign minister Andrii Deshchytsia said he had spoken in a phone call with Russian Foreign Minister Sergei Lavrov.
Russia denies providing any support to the militants, who have seized four government buildings in the east of the former Soviet republic, apparently emboldened by Russia's annexation of Ukraine's Crimea region last month.
Talking to his Russian counterpart Sergei Lavrov via telephone on April 12, Deshchytsya said that the ongoing actions of Russian agents in eastern regions aim at disrupting the Geneva meeting on stabilization of the situation in Ukraine.
The Ukrainian foreign minister's comments come the same day an armed group in military uniforms seized a police station in the city of Slovyansk in Ukraine's eastern Donetsk region.
Pro-Russian armed groups have been occupying the regional administration building in Donetsk and Security Service headquarters in the city of Luhansk since April 6-7, demanding the federalization of Ukraine.
Deshchytsya also confirmed his participation in the U.S-EU-Russia-Ukraine talks in Geneva scheduled for April 17.
Похоже, в Украине либо будет кровавое воскресенье в некоторых городах, либо начнется второй этап распада страны, либо и то, и другое.
— Павел Шеремет (@pavelsheremet) April 12, 2014
MT @MaxRTucker: Pro-#Russia separatists have got themselves some up to date Russian automatic rifles #Ukraine pic.twitter.com/REsJCLlHZo
— Olga Tokariuk (@olgatokariuk) April 12, 2014
Vor der besetzen Polizeistation Slowjansk. Dutzende Bewaffnete und Vermummte #Donetsk #Ukraine pic.twitter.com/gpDL8hjpM7
— Dirk Emmerich (@DEmmerich) April 12, 2014
Crowd at police station in #donetsk @Ruptly pic.twitter.com/cs7eoGhkcF
— Monika Kalinowska (@mkalinowskaa) April 12, 2014
BREAKING After #Slovyansk, police station in #KrasnyLiman seized by gunmen - @novostidnua reports citing witnesses http://t.co/K0Q9Rs25yL
— Myroslava Petsa (@myroslavapetsa) April 12, 2014
Reports of disturbances starting in yet another #Donetsk region town Kramatorsk #Ukraine
— Olga Tokariuk (@olgatokariuk) April 12, 2014
#Russia's invasion of the Eastern #Ukraine has begun unannounced
— Myroslava Petsa (@myroslavapetsa) April 12, 2014
Slaviansk, Kramatorsk, Krasny Liman...