Ukraine protesters have 'crossed the limits': Yanukovych

Ukraine's President Viktor Yanukovych said anti-government protesters had "crossed the limits" by taking to the streets to try to oust him from power, in an address to the nation Wednesday as deadly clashes raged in Kiev.

"The leaders of the opposition have disregarded the principle of democracy according to which we obtain power through elections and not on the street ... they have crossed the limits by calling for people to take up arms," he said.

"It is a flagrant violation of the law and those who are responsible will face justice."

Yanukovych's address came as riot police and protesters clashed at Kiev's Independence Square, the heart of anti-government protests for the past three months since he ditched an EU deal in favour of closer ties to Russia.

A day and night of bloody clashes left at least 18 people dead and saw flames engulf the square, which resembled a war zone.

The violence surged after the crisis appeared to have abated in recent days with concessions from both sides.

Yanukovych had granted amnesty to protesters, who in exchange vacated public buildings they had occupied.

However thousands of protesters rallied outside parliament Tuesday to press lawmakers to strip Yanukovych of his powers in a demonstration which slid into all-out clashes.

Yanukovych accused the opposition of calling "radicals on Maidan to an armed struggle" before lawmakers "could approve laws that would change Ukraine."

Maidan is the local name for Independence Square.

"They blocked parliament ... and demanded all the power for the opposition, and immediately.

"Without a mandate from the people, these so-called politicians tried to take power by violating the constitution through violence and murder."

Yanukovych said the opposition must either "distance itself from radicals" or "admit that it supports them".

"In that case we will speak to them differently."