Pro-Russia leader Milorad Dodik won a race to fill the Serb seat in Bosnia's three-member presidency, deepening ethnic divisions in the country that faced a brutal war some 25 years ago.
Preliminary official results from Sunday's election gave Dodik 56 per cent of the vote and his main opponent, Mladen Ivanic, 42 per cent. The projections were made with 44 per cent of ballots counted.
"The will of the people leaves no doubt what they want," Dodik said, adding that voters "punished" his opponent for his "servile policies toward the West."
Ivanic conceded defeat, but said "it's too early for some definitive results."
Complete official results are expected Monday.
The presidency also has a Muslim and a Croat member. Dodik advocates eventual separation of Serbs from Bosnia. His election deals a blow to efforts to strengthen the country's unity after the 1992-95 war.
Mladen Ivanic casts his ballot at a polling station in Banja Luka. Ivanic conceded defeat to Dodik. (Radivoje Pavicic/Associated Press)
The general election was seen as a test of whether Bosnia would move toward integration in the European Union and NATO or remain entrenched in rivalries stemming from the war that killed 100,000 people and left millions homeless.
Russian President Vladimir Putin had endorsed the openly anti-West Dodik. The United States has imposed sanctions on Dodik for actively obstructing efforts to implement the 1995 Dayton Accords that ended the Bosnian war.
Voters in Sunday's election filled positions in the complex governing system the peace accord created. The country consists of two regional mini-states — one Serb-run and another Muslim-Croat entity — with joint institutions in a central government.
Bosnian election workers are seen at a polling station in Sarajevo. Voters in Sunday's election filled positions in the country's complex governing system created by a 1995 peace accord. (Amel Emric/Associated Press)
Along with the Bosnian presidency, voters picked the Serb president and the two entities' parliaments and cantonal authorities.
The state election commission said a moderate candidate for the Croat member of the presidency, Zeljko Komsic, had 49 per cent of the votes, while nationalist contender Dragan Covic had 38 per cent.
Sefik Dzaferovic, from the ruling Party of Democratic Action, won the Muslim seat in the presidency.
More than half of Bosnia's 3.3 million eligible voters cast ballots, election officials said. The campaign was marred by divisive rhetoric and allegations of irregularities that fuelled tensions.
Election officials described the voting that took place as "extremely fair."