Francois Hollande told Russia's Vladimir Putin on Monday Ukraine must have a "peaceful transition", saying it was vital to ensure the country remained unified, the French president's office said.

Hollande also said the formation of a new government in Ukraine must lead to a presidential election and vital reforms, in a telephone conversation with the Russian president.

Freed Ukrainian opposition leader Yulia Tymoshenko will go for medical treatment in Germany next month as the ex-Soviet state struggles to resolve its worst crisis since independence, a statement on her website said.

"Former prime minister Yulia Tymoshenko has accepted the offer of treatment from German Chancellor Angela Merkel," the statement said, adding that she would seek treatment after attending the European People's Party congress starting in Dublin on March 6.

An international conference should be held on financial aid for Ukraine to keep the country from falling into disorder and default, the foreign minister of Greece, which holds the current EU presidency, said on Monday.

"It's our historical and moral duty to elaborate and to present together with the U.S., Russia and the competent international organizations a consolidated, integrated project," said Evangelos Venizelos.

The second most senior U.S. diplomat, Deputy Secretary of State William Burns, will visit Kiev Tuesday to support the new Ukrainian leadership and call for swift political and economic reform.

Monday's announcement makes Burns the highest-ranking Washington envoy to travel to the crisis-hit country since U.S. Assistant Secretary of State Victoria Nuland met with anti-government protesters in December.

The Organization for Security and Cooperation in Europe plans to set up an international group to support the transition of crisis-hit Ukraine, its current head said Monday.

Swiss Foreign Minister Didier Burkhalter, whose country assumed the rotating chairmanship of the 57-member body last month, said the group would include Kiev and "key" global actors.

British Foreign Secretary William Hague said on Monday he would visit Ukraine "shortly" and said the revolt-hit country needed urgent financial aid to prop up its economy.

Hague said his Russian counterpart Sergei Lavrov made no mention of military intervention when they spoke by phone Monday, and urged cooperation between the EU and Moscow.

U.N. Secretary General Ban Ki-moon called Monday for the preservation of Ukraine's "unity and territorial integrity" and sent an envoy to Kiev, his spokesman said Monday.

Ban reiterated an appeal to all sides to refrain from violence and to "uphold the principles of democracy and human rights" as they go forward to create an atmosphere conducive to free and fair elections, spokesman Martin Nesirky said.

French Foreign Minister Laurent Fabius on Monday urged Russia to continue to offer financial assistance to Ukraine, telling reporters in Beijing "there is no time to lose" for the crisis-hit country.

"What we know is that Ukraine's financial situation is very bad, that's for certain," Fabius said, as the global community discussed support for Ukraine, which has appealed for $35 billion in western aid.

A long-awaited EU-Ukraine deal cannot be signed until after the country's scheduled May elections, a spokesman for the bloc's executive arm, the European Commission, said Monday.

"The trade and investment agreement remains on the table," said Commission spokesman Olivier Bailly, referring to a wide-ranging political and trade pact at the root of Ukraine's three-month troubles.

The Russian Foreign Ministry on Monday strongly criticized the new Ukrainian leadership, saying it used dictatorial methods and discriminated against ethnic Russians.

"They have set a course to suppress those who do not agree in various regions of Ukraine using dictatorial and sometimes even terrorist methods," the ministry said in a statement. Moscow also slammed new legislation that it said aimed to "restrict the humanitarian rights of Russians".