Russia's Foreign Ministry has alleged that "dictatorial and sometimes terrorist methods" are being used in Ukraine to pressure dissenters against the country's new authorities.
It accused the parliament that ousted President Viktor Yanukovych of pushing through constitutional reforms without proper debate, and passing legislation curtailing the rights of ethnic Russians.
A ministry statement called for a "crackdown on the extremists who are trying to get established in power" in Ukraine.
The ministry also accused Western states, saying they were not worried about Ukraine's fate but instead engaged in "unilateral geopolitical calculations" in support of their own interests.
LIVE BLOG: Crisis In Ukraine
While the United States said Yanukovych was not "actively leading" Ukraine as president, the White House stopped short of endorsing anyone else as the country's legitimate leader.
Spokesman Jay Carney said on February 24 the Obama administration believed the Ukrainian parliament lawfully elected a new speaker, Oleksandr Turchynov.
But Carney declined to say whether Washington considers Turchynov to be Ukraine's legitimate acting leader since Yanukovych fled Kyiv in the face of deadly mass protests. Carney said the United States did not know Yanukovych's whereabouts.
The U.S. spokesman added that the United States is prepared to help Ukraine regain economic stability by providing support that complements assistance from the International Monetary Fund (IMF).
The European Commission, meanwhile, said on February 24 that it recognized Oleksandr Turchynov, an ally of formerly jailed Prime Minister Yulia Tymoshenko, as Ukraine's legitimate acting president.
The commission also said Ukraine could sign EU political cooperation and free-trade accords after a new government is formed through elections.
Yanukovych's decision not to sign those accords in November 2013 led to the movement that last week forced him to abandon his office and residence and flee Kyiv.
In other news, freed former Prime Minister Yulia Tymoshenko says she's planning to receive medical treatment in Germany. A statement on Tymoshenko's website said she had accepted an offer of treatment from German Chancellor Angela Merkel.
The statement said Tymoshenko would seek treatment in Germany after attending the European People's Party congress, which starts in Ireland on March 6.
Tymoshenko, who suffers from chronic back pain, left prison on February 22 after parliament voted on measures that resulted in her release.
Also on February 24, the parliament appointed Stepan Kubiv, a lawmaker with experience in banking, as the new head of the country's central bank.
Following his appointment, Kubiv promised to bring "transparency" to the operations of the National Bank. The previous bank chief, Ihor Sorkin, resigned following parliament's vote to oust Yanukovych as president.
Kubiv, 51, is a member of Tymoshenko's Batkivshchyna party and has headed several banks in the past, including Lviv KredoBank.
EU foreign-policy chief Catherine Ashton is currently visiting Kyiv, where she is expected to discuss ways to help Ukraine rebuild its economy.
Ukraine's acting finance minister said on February 24 that Ukraine will require around $35 billion in foreign aid over the next two years, and called for an international donors conference to be held urgently.
Earlier on February 24, Russian Prime Minister Dmitry Medvedev said Moscow had "serious doubts" about the legitimacy of many of Ukraine's government bodies following Yanukovych's ouster.
Medvedev said there was no one to deal with in Kyiv, as "masked men carrying Kalashnikovs" could not be partners for dialogue. He said recognizing the new authorities in Ukraine would be an "aberration."
"Some of our foreign partners, Western partners, think otherwise -- they consider these authorities legitimate. I don't know which constitution and what legislation they are reading from," Medvedev said. "I think it is an aberration of consciousness of some kind to give legitimacy to something that in essence is a result of an armed revolt."
After Yanukovych rejected the EU accords, Moscow extended a $15 billion aid package to Kyiv aimed at helping the government overcome Ukraine's debt crisis. That aid package now appears to be in doubt.
Warrant For Yanukovych
Ukraine's acting government has issued an arrest warrant for Yanukovych, accusing him of mass murder over the killings of dozens of antigovernment protesters by police.
Vitali Klitschko, one of the former opposition leaders, accused Yanukovych of going into hiding to escape responsibility.
"It's a remarkable situation when the most sought-after character in the country is the president of Ukraine, who is hiding and doing everything to flee from the country and to avoid the responsibility that he must bear," Klitschko said.
"I would like to emphasize that hundreds of victims are the responsibility of Yanukovych, who gave the orders [to disperse protesters with violence]."
Acting Interior Minister Arsen Avakov said that Yanukovych was last seen in the pro-Russian Black Sea peninsula of Crimea late on February 23 in a private residence in the Balaclava region.
He said that Yanukovych arrived there earlier that day accompanied by his head of administration, Andriy Klyuev.
Avakov said that Yanukovych relinquished his state-appointed bodyguards, then drove off to an unknown location.
With reporting by Reuters, AP, AFP, ITAR-TASS, Interfax, and RFE/RL's Tatar-Bashkir and Russian services