Serbia's leader Aleksandar Vucic has claimed a landslide victory in general elections, paving the way for another term as president and extending his decade-long rule in the Balkan nation.

"I have won 2,245,000 votes in the first round, that is the first round," Vucic announced on Sunday during a televised victory speech, saying he secured roughly 60 percent of the vote.

Zdravko Ponos, a retired army general representing the pro-European and centrist Alliance for Victory coalition was set to come second with 17.1 percent of the votes.

In the parliamentary vote Vucic's Serbian Progressive Party (SNS) was set to come first with 43.6 percent of votes, Ipsos and CeSID projections showed.

The United for Victory opposition alliance trailed behind with 12.9 percent of the votes.

As the SNS would likely fail to secure enough seats in the 250 parliament to rule alone, it will have to seek coalition partners.

The Socialist Party of Serbia, a long time ally of the SNS and the probable coalition partner, is seen third with 11.6 percent of the votes.

Vucic ran for the second five-year term on a promise of peace and stability just as Russia attacked Ukraine, which has put Serbia under pressure from the West to choose between its traditional ties with Moscow and aspirations to join the European Union (EU).

Russia-Ukraine conflict

Serbia is almost entirely dependent on Russian gas, while its army maintains ties with Russia's military.

Although Serbia backed two United Nations resolutions condemning Russia's assault on Ukraine, it refused to impose sanctions against Moscow.

A veteran politician who served as information minister in 1998 under former strongman Slobodan Milosevic, Vucic has transformed himself from a nationalist firebrand to a proponent of EU membership, but also of military neutrality and ties with Russia and China.

Ponos has accused Vucic of using the assault on Ukraine in his campaign to capitalise on people's fears.

Opposition and rights watchdogs also accuse Vucic and his allies of an autocratic style of rule, corruption, nepotism, controlling the media, attacks on political opponents and ties with organised crime.

Vucic and his allies have repeatedly denied all those allegations.