Nationalist candidates from rival ethnic groups have won Bosnia's three-seat presidency, underlining deep divisions 20 years after the Balkan state's civil war.

The main nationalist parties from the Bosniak, Serb and Croat communities looked to have held on to power on Monday, with more than 90 percent of votes counted.

Bakir Izetbegovic of the main Muslim SDA party and Dragan Covic of the Croat HDZ BIH party claimed to have won seats in the collective presidency.

The Serb seat remained undecided. Two nationalist candidates - opposition figure Mladen Ivanic and Zeljka Cvijanovic, the candidate of the Bosnian Serb ruling SNSD party - remain neck and neck.

Izetbegovic campaigned on the need for a strong, unified state. Covic wants the creation of a Croat entity within Bosnia. Cvijanovic is part of a Serb bloc that advocates Bosnia's dissolution.

Preliminary results for the 42-seat national assembly also showed dominance by nationalist parties, the Muslim SDA and the Serb SNSD.

The unwieldy power-sharing arrangement is part of a political system created by the US-brokered Dayton peace accord that ended a 1992-95 ethnic war in which an estimated 100,000 people were killed.

Sunday's general election, which also included parliamentary polls, laid bare widespread discontent over the economy and divisions along ethnic lines.

About 3.3 million Bosnians were eligible to vote on Sunday. Turnout was 54 percent - about two percent lower than in 2010 polls, reflecting widespread disenchantment with what is seen as the country's corrupt and inefficient political class.

Unemployment is at 44 percent and in February mass protests broke out against the government's failure to fight graft and enact the reforms required for Bosnia to enter the EU.

Under the complex Bosnian system, voters additionally chose members of the assemblies that oversee the country's two semi-autonomous halves - one the ethnic-Serb Republika Srpska and the other the Muslim-Croat Federation.

Serbs in their semi-autonomous region were also choosing a local president, with preliminary results showing the incumbent, Milorad Dodik, ahead by two points.

Source: Agencies