U.S. Secretary of State John Kerry is expected to meet with members of the Ukrainian opposition during his trip to Germany, which begins Friday.
U.S. officials say Kerry is to meet in Munich Saturday with opposition politician Arseny Yatsenyuk and former boxing champion-turned-activist Vitali Klitschko.
Meanwhile, Ukrainian protesters were expressing outrage after opposition activist Dmytro Bulatov, missing since January 22, was found outside Kyiv Thursday with cuts and bruises to his face. His supporters say he was kidnapped and held for days before being abandoned in a forest. They say he made his way to a nearby village, where he reached his friends by phone.
Ukrainian President Viktor Yanukovych has issued a statement accusing opposition leaders of escalating the political crisis. He said they are encouraging people to stand outside in freezing weather just to advance their political ambitions.
Mr. Yanukovych says the government has fulfilled its obligations to end the standoff, including a conditional amnesty for arrested protesters and replacing his prime minister.
Mr. Yanukovych announced Thursday he has gone on sick leave for an acute respiratory infection and fever.
Ukrainians took to the streets in November when President Yanukovych backed out of a trade deal with the European Union in favor of closer ties to Russia.
Human Rights Watch has called on Ukraine's international partners to press Ukraine to investigate what the group calls "serious human rights violations" perpetrated between January 19 through 22. The rights group says it has documented 13 cases in which police beat journalists or medical workers at the protests during that time. It says Ukrainian nongovernmental groups have documented 60 such cases.
Human Rights Watch says available evidence indicates that in many cases, police deliberately targeted journalists and medics.
Russian President Vladimir Putin said Wednesday he wants to wait for a new government in Ukraine before proceeding with a promised $15 billion loan to Ukraine along with substantial natural gas discounts.
Earlier this week, the Standard and Poor's rating agency downgraded Ukraine's credit rating, in part because of what it calls the country's "distressed civil society" and "weakened political institutions," and its questionable ability to repay its debts.