Ukrainian President Viktor Yanukovych on Friday announced early presidential elections and promised to bring opposition members into the government in a bid to defuse a deep crisis in which scores have been killed and hundreds injured.

He gave no time frame, however, and it's unclear whether his belated concessions will be enough to hold off protesters who have occupied a piece of Kiev and government buildings around the country in a nationwide battle over the identity of their country.

There was no immediate comment from opposition leaders, who were meeting among themselves after a marathon night of meetings with European diplomats.

The U.S., Russia and European Union are deeply concerned about the future of Ukraine, a nation of 46 million that has divided loyalties between Russia and the West. Shots rang out again Friday near the protesters' camp in Kiev, a day after the deadliest violence in Ukraine's post-Soviet history. It is unclear whether anyone was hurt or injured in Friday's incident.

``As the president of Ukraine and the guarantor of the Constitution, today I am fulfilling my duty before the people, before Ukraine and before God in the name of saving the nation, in the name of preserving people's lives, in the name of peace and calm of our land,'' the president said in a statement on his website.

Yanukovych also promised constitutional reforms trimming presidential powers, a key demand of protesters.

The opposition has rejected similar invitations to join the government in the past, saying that constitutional reform giving parliament greater powers has to be passed first.

Polish Foreign Minister Radoslaw Sikorski, who is involved in the negotiations in Kiev, called for calm. He tweeted that it's a ``delicate moment for the settlement and all must remember you don't get 100 percent in a compromise.''

All this was not enough for some protesters, who accused the president of trying to buy time and want him out immediately.

Yanukovych, who triggered the protests in November by aborting a pact with the European Union in favor of close ties with Russia, has refused to step down.

``We haven't achieved anything yet, neither Europe, nor freedom, nor new leadership. We will stop our fight only after Yanukovych resigns. He has blood on his hands,'' said protester Stepan Rodich, speaking at the Independence Square known as Maidan on Friday.

Several regions in the west of the country are in open revolt against the central government, while many in eastern Ukraine back the president and favor strong ties with Russia, their former Soviet ruler. (AP)