Joe Biden tells Ukrainian president to call police off as anti-protester violence escalates
An anti-government activist stands on a barricade of the opposition in Kiev on Jan. 28, 2014 [AFP]

US Vice President Joe Biden on Tuesday intervened as a political crisis in Ukraine turned deadly, calling President Viktor Yanukovych and saying he should withdraw government forces who stormed a protest camp.

"Vice President Biden called Ukrainian President Viktor Yanukovych today to express grave concern regarding the crisis on the streets of Kiev. He called on President Yanukovych to pull back government forces and to exercise maximum restraint," a White House statement said.

US officials had watched with alarm as television pictures showed flames engulfing a camp manned by opposition protesters in central Kiev after government forces moved in on the bloodiest day in the standoff so far, which saw at least 12 people killed.

The White House said Biden made clear in the telephone call that Washington condemned violence by any side "but that the government bears special responsibility to de-escalate the situation.

"The vice president further underscored the urgency of immediate dialogue with opposition leaders to address protesters' legitimate grievances and to put forward serious proposals for political reform.

"The United States is committed to supporting efforts to promote a peaceful resolution to the crisis that reflects the will and aspirations of the Ukrainian people."

Biden has repeatedly reached out to Yanukovych and opposition leaders in an effort to help bring an end to the political crisis.

Tuesday's violence marked the first such outburst since mid-January in the Ukrainian capital, which has been wracked by anti-government demonstrations since Yanukovych in November rejected a European Union pact in favor of closer ties with historical master Russia.

Watch a report from Kiev, as aired on CNN on Tuesday, below.