Nikolic had pleaded not guilty to the charges, and branded the proceedings a "political trial".
Some observers were spooked by the presidential victory of Mr Nikolic, who once espoused a form of extreme nationalism.
ECONOMIST: Serbia��s presidential election: The gravedigger��s victory | The
Tomislav Nikolic had recently persuaded his Serbian Radical Party to approve the ratification of an important agreement with the European Union.
Serbia's electoral commission said Mr Tadic had secured 50.5% of the votes compared to Mr Nikolic's 47.7% in a closely monitored election.
"I kneel and ask for forgiveness, " President Tomislav Nikolic told Bosnian TV.
In parliamentary elections on May 6th, Mr Nikolic's centre-right Serbian Progressive Party (SNS), won, taking, with its allies, 73 of the 250 National Assembly seats.
ECONOMIST: Serbia��s presidential election: The gravedigger��s victory | The
Mr Nikolic resigned in protest, both from his position as de facto leader of the party, and as the head of its group in parliament.
Mr Nikolic is officially the deputy president of the party as its leader, Vojislav Seselj is facing charges at the international war crimes tribunal in The Hague.
As president, Mr Nikolic has already made some baffling statements.
Ivan Nikolic, 30, was convicted over the killing of two Kosovo Albanians in 1999 in a village located between the northern Kosovo town of Podujevo and the capital Pristina.
Nikolic was found guilty of "breaking international rules of war by killing two ethnic Albanian civilians, committing war crimes against the civilian population, " said judge Dragan Tacic, delivering the sentence.
But Mr Nikolic's victory has changed the dynamics.
ECONOMIST: Serbia��s presidential election: The gravedigger��s victory | The
Yet as kingmaker Mr Dacic dropped his alliance with the Democratic Party of Boris Tadic in favour of the Serbian Progressive Party (SNS) led by Tomislav Nikolic, who defeated Mr Tadic in the presidential election.
The BBC's Nick Thorpe in Belgrade says Mr Nikolic had steered his party towards the centre of Serbian politics, focusing on social issues such as unemployment and poverty, rather than the militant nationalism of the past.
If Mr Nikolic were to win this election, he could be expected to share Prime Minister Vojislav Kostunica's view that any EU mission in Kosovo without UN endorsement would be illegal and everything should be done to make life difficult for it.
This is because the largest Serbian opposition group, the ultranationalist Radical Party, has imploded thanks to an internal war between the devotees of Vojislav Seselj, currently standing trial for war crimes at the United Nations' tribunal in The Hague, and the allies of the more pragmatic Tomislav Nikolic, who led the party within Serbia.
ECONOMIST: The Serbian president has become unusually powerful
应用推荐