kraine has issued an arrest warrant for President Viktor Yanukovych as Russia declared the situation in its neighbour was a "real threat" to its interests.
Ukraine's acting interior minister said Mr Yanukovych, whose exact whereabouts are unknown, and other officials are wanted by police for "mass murder" of peaceful citizens.
Arsen Avakov said the deposed leader had left a private residence in Balaclava, in the Russian-speaking Crimea region, for an unknown destination with one of his aides.
Spokesmen for the Interior Ministry and Security Service in Crimea said they had no information to support reports from opposition politicians and a news website that the president had been arrested or seen with Russian marines there.
Western governments are scrambling to provide support for Ukraine amid fears that Russia could send in troops to intervene in support of its ousted ally.
Russian prime minister Dmitry Medvedev, however, said their backing of the interim government was an "aberration".
"We do not understand what is going on there. There is a real threat to our interests and to the lives of our citizens," Russian news agencies quoted him as saying.
"There are big doubts about the legitimacy of a whole series of organs of power that are now functioning there."
Russia's Foreign Ministry accused Ukraine's opposition of using "dictatorial and sometimes terrorist methods," while Sergei Lavrov said it "had in effect seized power in Kiev, refused to disarm and continued to place its bets on violence".
The Foreign Ministry accused the West of engaging in "unilateral geopolitical calculations" and said the concerns of Russian-aligned areas in Crimea, the south and east of the country should be listened to.
Russia's economy minister has also warned Kiev against signing a partnership agreement with the EU - threatening to hike import duties if Ukraine looks to forge closer ties with the west.
