Ukraine-sceptic government ally Peter Pellegrini won Slovakia's presidential election Saturday against pro-Western diplomat Ivan Korcok.

Opposition-backed Korcok conceded defeat as nearly complete results showed he had received 47 percent of the vote against former prime minister Pellegrini's 53 percent.

"I am honestly disappointed. But I'm an athlete, so I can respect even this result. I want to congratulate the winner," Korcok said.

"I want to express my belief that Peter Pellegrini will be independent and will act according to his own convictions and without orders," he added.

Divisions over the Ukraine war dominated the run-off vote given the starkly differing views of the conflict by the two candidates for the post that is largely ceremonial.

Russia's invasion of Ukraine became a fixture of the electoral campaign in the country of 5.4 million people after populist Prime Minister Robert Fico, Pellegrini's ally, questioned Ukraine's sovereignty and called for peace with Russia.

Ahead of the run-off, Pellegrini said Slovak politicians were divided into those wanting to continue the war or those advocating peace talks.

"I belong to the latter," he told AFP.