SIMFEROPOL, Ukraine: Ukraine's acting government issued a warrant Monday for the arrest of President Viktor Yanukovych, last reportedly seen in the pro-Russian Black Sea peninsula of Crimea, accusing him of mass crimes against protesters who stood up for months against his rule.

Calls are mounting in Ukraine to put Yanukovych on trial, after a tumultuous presidency in which he amassed powers, enriched his allies and cracked down on protesters. Anger boiled over last week after snipers attacked protesters in the bloodiest violence in Ukraine's post-Soviet history.

The turmoil has turned this strategically located country of 46 million inside out over the past few days, raising fears that it could split apart.

The parliament speaker is suddenly nominally in charge of a country whose economy is on the brink of default and whose loyalties are torn between Europe and longtime ruler Russia.

The acting finance minister said Monday that the country needs $35 billion (25.5 billion euros) to finance government needs this year and next and expressed hope that Europe or the United States would help.

Ukraine's acting interior minister, Arsen Avakhov, said on his official Facebook page Monday that a warrant has been issued for the arrest of Yanukovych and several other officials for the ''mass killing of civilians''.

At least 82 people, primarily protesters, were killed in clashes in Kiev last week.

Avakhov says Yanukovych arrived in Crimea on Sunday, relinquished his official security detail and then drove off to an unknown location, turning off all forms of communication.

''Yanukovych has disappeared,'' he said.

Earlier, after signing an agreement Friday with the opposition to end a conflict that had turned deadly, Yanukovych had fled the capital of Kiev for eastern Ukraine. Avakhov said he tried to fly out of Donetsk but was stopped, then went to Crimea.

Tensions have been mounting in Crimea, where pro-Russian protesters raised a Russian flag on a city hall in one town and scuffled with police. Russia maintains a big naval base in the Crimean port of Sevastopol that has tangled relations between the countries for two decades.

The tensions seem to be driven by Russia, though a representative of the pro-Moscow Russian Unity party played down fears that Crimea could secede, saying that they want to maintain ties with Moscow and a Putin-driven Customs Union but do not want Crimea to break away.

Yanukovych set off a wave of protests by shelving an agreement with the European Union in November and turning toward Russia, and the movement quickly expanded its grievances to corruption, human rights abuses and calls for Yanukovych's resignation.

''We must find Yanukovych and put him on trial,'' said protester Leonid Shovtak, a 50-year-old farmer from the western Ivano-Frankivsk region who came to Kiev's Independence Square to take part in the three-month protest movement. ''All the criminals with him should be in prison.''

The speaker of parliament, Oleksandr Turchinov, assumed the president's powers Sunday, even though a presidential aide told The Associated Press on Sunday that Yanukovych plans to stay in power.

Meanwhile, Yanukovych's archrival, Yulia Tymoshenko, blond-braided heroine of the 2004 Orange Revolution, is back on the political scene after having been freed from prison.

Turchinov said top priorities include saving the economy and ''returning to the path of European integration'', according to news agencies. The latter phrase is certain to displease Moscow, which wants Ukraine to be part of a customs union that would rival the EU and bolster Russia's influence. Russia promised Ukraine a $15 billion bailout after Yanukovych backed away from the EU deal but then froze disbursements because of political unrest.

The EU is reviving efforts to strike a deal with Ukraine that could involve billions of euros in economic perks. EU foreign policy chief Catherine Ashton is visiting Kiev on Monday and Tuesday.

Ukraine's acting Finance Minister Yuri Kolobov said in a statement Monday that Ukraine hopes for an emergency loan within the next two weeks from foreigner partners such as the United States and Poland, and called for an international donors conference to discuss aid to Ukraine.

US Ambassador Geoffrey Pyatt said Sunday the US is ready to help Ukraine get aid from the International Monetary Fund.

The protest movement has been in large part a fight for the country's economic future — for better jobs and prosperity. Ukraine's trading partners are also interested in its large potential consumer market, educated workforce, significant industrial base and good natural resources, in particular rich farmland.

Ukraine has struggled with corruption, bad government and short-sighted reliance on cheap gas from Russia. Political unrest has pushed up the deficit and sent exchange rates bouncing, and may have pushed the economy back into a recession.

Per capita economic output is only around $7,300, even adjusted for the lower cost of living there, compared to $22,200 in Poland and around $51,700 in the United States. Ukraine ranks 137th worldwide, behind El Salvador, Namibia, and Guyana.