KIEV, Ukraine — Ukraine's president urged all voters to take part in Sunday's presidential election to "cement the foundation of our nation," even as pro-Russia insurgents battled government forces Friday in eastern Ukraine.
In Russia, President Vladimir Putin blamed the West for plunging Ukraine into what he described as "chaos and a full-scale civil war."
In a live televised address, acting President Oleksandr Turchynov, who is not running, emphasized the importance of the vote to choose a new leader for Ukraine.
"Today, we are building a new European country the foundation of which was laid by millions of Ukrainians who proved that they are capable of defending their own choice and their country," Turchynov said. "We will never allow anyone to rob us of our freedom and independence, turn our Ukraine into a part of the post-Soviet empire."
Authorities in Kiev had hoped that a new president would unify the divided nation, where the west looks toward Europe and the east has strong traditional ties to Russia. But they have now acknowledged it will be impossible to hold the vote in some areas in the east — especially in Donetsk and Luhansk, where insurgents have declared independence and pledged to derail the vote. Election workers and activists say gunmen there have threatened them and seized their voting materials.
Joao Soares, coordinator for an observation mission of the Organization for Security and Cooperation in Europe, said Friday he expects problems with voting in "less than 20 percent of the polling stations."
Twenty-one candidates are competing Sunday to become Ukraine's next leader. Polls show billionaire candy-maker Petro Poroshenko with a commanding lead but falling short of the absolute majority needed to win in the first round; his nearest challenger is Yulia Tymoshenko, the divisive former prime minister, who is trailing by a significant margin.
If no one wins in the first round, a runoff will be held on June 15. Most polls predict Poroshenko's victory in that contest.
Speaking Friday at an investment forum in St. Petersburg, Putin blamed the West for encouraging a "coup" in Ukraine, when the nation's pro-Russian president was chased from power after months of protests.
At a separate security conference in Moscow, Russian Foreign Minister Sergey Lavrov urged the West to reach a settlement based on mutual interests.
"If we sincerely want to help the Ukrainian people overcome this crisis, it's necessary to abandon the notorious zero-sum games, stop encouraging xenophobic and neo-Nazi sentiments and get rid of dangerous megalomania," Lavrov said.
Russia annexed Ukraine's southern Crimea Peninsula in March, triggering the worst crisis in relations with the West since the Cold War. Pro-Russian insurgents also have seized government buildings in eastern Ukraine and fought government troops for more than a month.
In the deadliest attack yet, pro-Russia insurgents attacked a military checkpoint and killed 16 soldiers Thursday, casting a shadow over the presidential vote.
The head of the General Staff of the Russian military, Gen. Valery Gerasimov, on Friday criticized Ukrainian authorities for what he said was using artillery and other heavy weapons against civilians. He also charged that radical paramilitary forces and private security companies were spearheading the Ukrainian offensive.
While many in eastern Ukraine resent the government in Kiev, they are also growing increasingly exasperated with the insurgents, whom they blame for putting civilians in the crossfire.
The village of Semenovka on the outskirts of Slovyansk, a city that has been the epicenter of clashes for weeks, has seen continuous shelling by the Ukrainian government forces retaliating to rebel fire.
Early Friday, a house was destroyed by mortar fire that came from Ukrainian government side, but locals reported no casualties.
Shelling continued later in the day, targeting Slovyansk, where several other buildings were also damaged. There was no word of casualties.
Isachenkov reported from Moscow. Alexander Zemlianichenko in Slovyansk also contributed to this report.