Ukraine’s interior minister, Arsen Avakov made the announcement in a statement posted on the social networking website Facebook on Monday.

"An official case for the mass murder of peaceful citizens has been opened," the statement, posted on Avakov’s Facebook profile said. "Yanukovych and other people responsible for this have been declared wanted."

At least 82 people were killed in clashes between security forces and demonstrators last week, including many who were shot dead by police snipers.

The exact whereabouts of Yanukovych, whom the Ukrainian parliament voted to remove from office on Saturday, remained unclear on Monday, although Avakov said he had been last sighted in the eastern, largely pro-Russian region of Crimea.

Yanukovych, whose decision last November to balk at signing an association agreement with the European sparked weeks of, at times, violent protests against his rule, fled the capital, Kyiv, shortly after lawmakers voted to oust him.

Despite the vote, Yanukovych has said through an aide that he plans to remain in office.

The parliamentary speaker, Oleksandr Turchynov, who assumed the presidency on an interim basis on Sunday, said his top priorities were to rescue Ukraine’s ailing economy and "returning to the path of European integration."

EU, US vow support

The European Union and the United States both vowed over the weekend to lend financial support to the transitional government. The EU’s foreign policy coordinator Catherine Ashton was scheduled to travel to Kyiv on Monday to discuss "measures to stabilize the economic situation."

Turchynov also said Kyiv wanted to put dialogue with Moscow on a "new, equal and good-neighborly footing that recognizes and takes into account Ukraine's European choice."

Russian President Vladimir Putin has said that Moscow intended to help Ukraine navigate a political transition, working alongside both the EU and the US.

pfd/hc (AP, Reuters)