KIEV, Feb. 4 - President Viktor Yanukovych, battling mass unrest against his rule, faced demands from the opposition on Tuesday for a constitutional change that would seriously curtail his powers.

Yanukovych was still weighing who to name as his new prime minister to calm the crisis on the streets. Rumors swirled that he could be considering his powerful hardline chief of staff Andriy Klyuev.

Vitaliy Klitschko, the leader of the opposition Udar party, came out of a meeting with the president accusing him of courting more unrest by stalling.

"The head of state is taking an irresponsible position because, by his actions, he is provoking people to take radical action and the democratic world to take sanctions," he said, Reuters reported.

As the Ukrainian central bank intervened again to stop heavy demand for dollars weakening the hryvnia currency, Ukraine sharply criticized EU heavyweight Germany after its foreign minister said sanctions should be used as a threat unless a political solution was found soon to end the crisis.

At least six people have been killed in the past two weeks in unprecedented politically-linked violence in Kiev, whose center is now a heavily-barricaded fortified protest zone.

Fierce clashes between riot police and squads of radical protesters have prompted global concern that the ex-Soviet republic, a large buffer territory of 46 million people between Russia and the EU, might plunge into civil war.

Though there has been no violence in Kiev for several days, Western governments have warned Yanukovych that it risks flaring up again unless he can find a compromise with the opposition.

Yanukovych triggered the uprising on the streets last November when he walked away from a trade deal with the European Union in favor of closer economic ties with Russia.

Though his move was rewarded with a $15-billion offer of credits and cheap gas from Moscow for Ukraine's ailing economy, it provoked outrage among millions of Ukrainians who dream of a European future for their country.

Caught in a geopolitical tug-of-war between Russia and the West, Yanukovych faces tough choices over his future alliances.

The United States and its EU allies are backing the protesters, though largely with words rather than deeds or cash. Russian President Vladimir Putin's hefty economic lifeline comes with a condition that he forms a government that suits Moscow. (rt/ez)