The Ukrainian president, Viktor Yanukovich, is wanted by police for the "mass murder of peaceful civilians", according to an arrest warrant that is being persued by the country's acting interior minister.
Arsen Avakov said on Monday that an arrest warrant was being drafted for Yanukovich, who fled the capital Kiev on Saturday following months of political upheaval that escalated into bloodshed.
"A criminal case has been launched over the mass murder of peaceful civilians. Yanukovich and a number of other officials have been put on a wanted list," Avakov said in a statement on his Facebook account. However, the warrant had yet to be finalised by the attorney general.
The statement was followed by comments by the Russian prime minister, Dmitry Medvedev, who said the Ukraine's new authorities came to power in an "armed mutiny".
Reuters news agency said that Yanukovich was last seen in a private residence in Balaclava, Crimea. Al Jazeera's Hoda Abdel-Hamid, reporting from Kiev, said there was confusion over the arrest warrant and of Yanukovich's precise whereabouts.
On Monday afternoon acting president Oleksander Turchinov said the presidential election campaign would begin February 25, when the election commission would start registering candidates.
On Sunday, Turchinov said the country was ready for talks with Russia to try to improve relations, but made clear that Kiev's European integration would be a priority. He said that Ukraine's new leadership was ready to put Kiev-Moscow relations on a "new, equal and good-neighbourly footing that recognises and takes into account Ukraine's European choice".
"Another priority ... is the return to the path of European integration," he said, in an address to the nation.
Hours later, Russia recalled its ambassador in Ukraine to Moscow. "Due to the deteriorating situation in Ukraine and the need for a comprehensive analysis of the situation, the decision was made to recall the Russian ambassador to Ukraine for consultations in Moscow," the Russian foreign ministry said in a statement.
In a phone call on Sunday with his Russian counterpart Sergei Lavrov, US Secretary of State John Kerry "underscored the United States' expectation that Ukraine's sovereignty, territorial integrity and democratic freedom of choice will be respected by all states".
Meanwhile, the Interfax news agency reported that Valery Gerasimov, Russia's senior army general and Philip Breedlove, the top NATO military commander have spoken over the telephone on Monday and expressed concern over the situation in Ukraine.
Ukraine's parliament voted to temporarily hand over the duties of president to Turchinov, the speaker of the assembly, who told deputies to agree on the formation of a national unity government by Tuesday.
The development came one day after parliament voted to oust Yanukovich from the presidency, setting May 25 as the date for new presidential elections, and two days after an agreement was reached with Yanukovich on the need to form a national unity government.
Turchinov is a close ally of former Prime Minister Yulia Tymoshenko, the president's main rival.
Parliament also voted to oust the foreign minister and was told by the country's acting prosecutor that an order had been given to detain the former incomes minister and the former prosecutor-general.
Andriy Shishatskiy, the governor of Donetsk, one of the biggest cities in Russian-speaking eastern Ukraine, said that he recognises new authorities in Kiev, saying that it is the country's "only legitimate body now".
"A lot of mistakes, including tragic mistakes, have been made. And the most horrible thing is they led to people's deaths. For this the president will undoubtedly be taken to account," said Shishatskiy.
The whereabouts of Yanukovich remained unclear on Sunday, a day after he left the capital and rival Tymoshenko was freed from prison, returning to Kiev to address a massive, adoring crowd.
The centre of Kiev, meanwhile, was calm on Sunday. Protesters on Saturday took control of the presidential administration building, and thousands of Ukrainians roamed the suddenly open grounds of the lavish compound outside Kiev, where Yanukovich was believed to live.