Nationalist parties have won a weekend election in Mostar, the Bosnian city that symbolizes the communal splits and broken politics that have haunted the country since the 1990s war.

Sunday's vote was the first local election in 12 years in Mostar, which remains divided along ethnic lines between predominately Catholic Croats and Muslim Bosniaks.

The main Croat party, the HDZ, won in the city's Croat zones and was also leading across Mostar, with more than 37% of the vote, according to preliminary results announced by the electoral commission Monday.

The country's main Bosniak coalition, led by the Muslim Party of Democratic Action (SDA), was trailing behind with 29%.

The city of 100,000 people has not had a local vote since 2008 because the two parties could not agree on the legalities around organizing an election.

Contact between the two communities in Mostar – which is known for its historic World Heritage Site, Stari Most – is still minimal in what was once the former Yugoslavia's most cosmopolitan city.

According to HDZ head Dragan Covic, the candidate who headed the party's election list, Mostar doctor Mario Kordic, will become mayor.

"We want to transform Mostar into a European town, that is the message for all Mostar's inhabitants, regardless of their nationality," Covic said Sunday.

The new mayor will be elected by the 35-seat municipal council that should be formed after the results are confirmed, which could take several weeks.

The two nationalist parties have run the city together without interruption since the end of Bosnia's 1992-1995 war which left 100,000 people dead.

Sunday's vote took place after a Mostar resident sued Bosnia-Herzegovina at the European Court of Human Rights, which ordered the state to organize municipal elections in the city.

But Irma Baralija's court victory failed to transfer to the ballot box, where turnout on Sunday was only 55%.

And her Nasa Stranka (Our Party), which was allied with another multiethnic grouping for the election, scored just 11%.

"I know it is not the end of nationalism or nationalists, but I am convinced it is the beginning of the end," said Nasa Stranka leader Pedja Kojovic.