- Yanukovych is said to be feeling good after treatment
- Yanukovych went on sick leave Thursday with "acute respiratory disease"
- Thousands of protesters remain out in Kiev streets on Sunday
- Ukraine rattled by protests, then clashes, since November
Ukraine's President Viktor Yanukovych will return to work on Monday, after taking ill amid political unrest that has paralyzed the eastern European country.
Yanukovych went on sick leave on Thursday with "acute respiratory disease," his office said. He is now feeling "good" after treatment and his condition has been assessed as "satisfactory," a statement on the presidential website said.
Ukraine has been plunged into a deep political crisis that in the last week saw the Prime Minister and Cabinet resign, a controversial anti-protest law repealed, and the President signing off on a contested amnesty bill for anti-government protesters.
Thousands of demonstrators have packed Kiev's Independence Square since November, when Yanukovych reversed a decision to sign a long-awaited trade deal with the European Union and turned instead toward Russia.
The government's attempts to crack down on protests appear only to have strengthened the opposition's resolve. Violent confrontations flared after a sweeping anti-protest law was signed two weeks ago, followed by an uneasy standoff on the streets as the battle in the political arena has heated up.
On Sunday, the demonstrators showed no signs of leaving, again massing in Independence Square despite freezing temperatures.
Despite concessions last week from Yanukovych, including repeal of the controversial law, Ukraine's opposition parties continue to call for constitutional reforms to shift power away from the president.
They say the new amnesty bill -- which only comes into force if protesters vacate seized government buildings and unblock roads and squares -- is unacceptable.
A special parliamentary session is scheduled for Tuesday.
Speaking at the Munich Security Conference on Saturday, U.S. Secretary of State John Kerry said the United States and the European Union "stand with the people of Ukraine" in their fight for the right to choose alliances with countries other than Russia.
After his address, Kerry met with three Ukrainian opposition leaders -- Arseniy Yatsenyuk of the Fatherland party, Vitali Klitschko of the UDAR party and Petro Poroschenko of the "Euromaidan" street protest movement -- the State Department said.
Ukraine, a country of 45 million people, is split between pro-European regions in the West and a more Russia-oriented East.
Also speaking at the conference, Russian Foreign Minister Sergey Lavrov said the United States and the European Union appeared to be trying to push their own ideas on Ukraine.
Deadly clashes last month were an escalation of weeks of largely peaceful public protests prompted by Yanukovych's decision in November to spurn a planned trade deal with the European Union and favor Russia instead.
He and Russian President Vladimir Putin agreed on a $15 billion deal for Russia to buy Ukrainian debt and slash the price of natural gas.
Yanukovych has resisted calls for him to step down and defended the government's handling of the political crisis.