Serbia's governing populists claimed a sweeping victory in Sunday's snap parliamentary elections.

According to a near-complete preliminary tally published Monday by the state election commission, President Aleksandar Vucic's Serbian Progressive Party (SNS) won 47% of the vote.

The largest opposition group, Serbia Against Violence (SPN), picked up 23%.

How significant is the victory by Vucic's party?

Vucic's name was not on the ballot, as it was not a presidential election, but the vote was widely seen as a referendum on his leadership after a turbulent year for the country.

Tensions with neighboring Kosovo, which declared independence in 2008, have escalated. And two back-to-back mass shootings claimed the lives of 18 people in Serbia. 

The shootings rattled Vucic's support, yet his right-wing populist SNS maintained a commanding position following the vote.

"We will have an absolute majority in [the 250-seat] parliament with 127 seats," President Aleksandar Vucic told reporters. 

The Kremlin welcomed the result, saying Moscow hoped it would lead to the "further strengthening of friendship" between Russia and Serbia.

Observers flag voting irregularities

Some electoral observers and independent media reported irregularities on voting day.

One report claimed that ethnic Serbs from Bosnia and Herzegovina gathered to vote in a sports hall in Belgrade that was not an official polling station.

Observers from the Center for Research, Transparency and Accountability expressed "the highest concern" over allegations that illegal voters were bussed into Belgrade from other countries.

"The concentration of buses, minivans and cars was observed on several spots in Belgrade, transferring voters to polling stations across the city to vote," the civil society watchdog said.

Monitors, including some from the Organization for Security and Co-operation (OSCE), reported cases of "vote buying" and "ballot box stuffing."

"Election day was smooth but marred by isolated instances of violence, procedural irregularities and frequent allegations of organizing and busing of voters to support the ruling party in local elections," said a statement by the International Election Observation Mission.

The opposition said it would lodge official complaints and called for a street protest in Belgrade on Monday night.

Authorities have rejected claims of any wrongdoing, and acting Prime Minister Ana Brnabic dismissed the reports as "lies that are intended to spread panic."

Ruling party challenged in local elections

The parliamentary vote coincides with local elections taking place in most municipalities, the capital Belgrade, and the northern province of Vojvodina.

The Belgrade vote is shaping up to be a crucial battleground between the SNS and the centrist SPN coalition.

The movement was formed in the wake of the mass shootings, which pushed hundreds of thousands of anti-government protesters to the streets for months.

Vucic has dismissed the rallies as a foreign plot, often warning that Serbia would be left directionless without him.

"It's not about me leaving power, but about them destroying everything," he told supporters at a recent rally. 

"It would take us 20 years to fix everything ... That's why we'll beat them more convincingly than ever."

zc, rmt/lo (AFP, Reuters)