Pro-Russian rebels in eastern Ukraine
Pro-Russian rebels in eastern UkraineReuters

Ukrainian chocolate baron Petro Poroshenko claimed a resounding victory on Sunday in Ukraine's presidential election and immediately vowed to end a bloody pro-Russian uprising that thwarted voting across swathes of the eastern part of the country, AFP reports.

The pro-Western self-made billionaire won close to 56 percent of the vote, according to the report.

"My first decisive step will be aimed at ending the war, ending chaos, and bringing peace to a united and free Ukraine," the 48-year-old said at a press conference in Kiev.

"I am certain that our decisive actions will bring fairly quick results," he said in reference to an outcome that analysts said hands him a strong mandate to deal directly with Russian President Vladimir Putin.

Despite his commanding lead, the armed rebellion meant voting was largely blocked in two eastern regions that make up 15 percent of the national electorate, raising concerns about the legitimacy of his mandate across the entire country.

Official confirmation of the results should avoid the need for a June 15 runoff that would have extended political uncertainty in the country.

The exit polls put Poroshenko more than 30 points ahead of nearest rival Yulia Tymoshenko, the former prime minister who spearheaded the 2004 pro-democracy Orange Revolution but then became embroiled in corruption scandals that saw her put behind bars by the old pro-Russian regime.

U.S. President Barack Obama praised Ukrainians for showing courage by voting in the face of the threat posed by militants who have seized about a dozen cities and towns in a seven-week rebellion.

"Despite provocations and violence, millions of Ukrainians went to the polls throughout the country, and even in parts of eastern Ukraine, where Russian-backed separatist groups sought to disenfranchise entire regions, some courageous Ukrainians still were able to cast their ballots," the White House quoted Obama as saying, according to AFP.

Putin issued no immediate comment and instead spent Sunday evening in Belarus watching his country compete in the final of the ice hockey world championship.

On Saturday, Putin reassured the public that, despite months of violence in eastern Ukraine, Moscow is actively looking to maintain stability.

"By all means, we will respect the choice of the Ukrainian people and will be working with authorities formed on the basis of this election," he told foreign journalists during an international economic forum in St. Petersburg.

landmark deal reached last month between Russia, the U.S. and the European Union (EU) called for the separatists, who have been seizing government buildings in eastern Ukraine for several days, to disarm and stand down - in exchange for amnesty.

Putin has also stated multiple times that he would retract his forces from the border - pacifying the West - on the condition that separatists stand down. 

The pro-Russian protesters have largely ignored the deal, however, claiming that the agreement does not apply to them.