Russia not to adjust policy over sharp statements from West

Meanwhile, he nodded to Merkel's proposal to expand the existing mission of the Organization for Security and Cooperation in Europe (OSCE) in Ukraine and send more observers, primarily to the country's east.

Merkel also stressed the need to hold direct talks between the Russian and Ukrainian governments in order to resolve the existing issues.

Also on Sunday, Russian Foreign Minister Sergei Lavrov confirmed to US Secretary of State John Kerry via a telephone conversation that Moscow's position on Crimea referendum remained unchanged.

Lavrov urged the US side to place its full influence on Kiev authorities to "stop mass lawlessness and arbitrariness against the Russian speaking population."

"Recently, ultra-nationalist and radical forces stepped up the activities in Ukraine's southeast ... Radicals' actions seriously destabilize the situation," the Interfax news agency quoted Lavrov as saying.

The two diplomats "agreed to continue contacts to search for ways to settle the crisis in Ukraine in order to launch a constitutional reform in the country in respect of all Ukrainian regions."

Crimea, a Ukrainian autonomous republic, is holding a referendum Sunday over its future status. More than 1,000 polling stations will remain open from 8 am to 8 pm local time.

An exit poll by the Crimean Republic Institute for Political and Social Studies indicated reportedly that 93 percent of voters in the Autonomous Republic of Crimea were in favor of reunification with Russia.

About an hour to go before the referendum ends, Crimeans in Simferopol, the capital city of the peninsula, were already seen streaming toward the central city square for celebration.

Meanwhile, a joint statement issued Sunday by European Council President Herman Van Rompuy and European Commission President Jose Manuel Barroso called the referendum in Crimea "illegal and illegitimate", saying its outcome "will not be recognized."

In the US, a White House spokesman said on Sunday that the referendum has been "administered under the threats of violence and intimidation from a Russian military intervention that violates international law."