Serbian election authorities on Thursday annulled the votes cast at a handful of polling stations amid allegations of irregularity, in a move that could significantly impact parliamentary elections held last weekend.
The vote will be repeated in at least 15 polling stations, affecting around 18,000 of the 6.7 million registered voters. The election commission was also reviewing dozens of other complaints and recounting ballots from as many as 100 polling stations.
Although the voided votes make up a tiny fraction of national total, they may be vital to two parties that stand to be eliminated if they do not pass Serbia's 5-per-cent threshold.
The election authority's decision also means the final result can only be announced after the vote is repeated.
With 98 per cent of the ballots counted, Conservative Prime Minister Aleksandar Vucic's Progressive Party (SNS) has 48.2 per cent of the vote, as much as in previous elections two years ago.
The ruling party has already secured its majority with 131 of the 250 seats in parliament, albeit with 27 seats fewer than before the elections.
According to Serbia's electoral system, any votes cast for parties that do not pass the 5-per-cent mark are distributed among those parties that do.
In previous elections, the SNS benefited from a large number of non-qualifiers, while on Sunday a surprising seven parties cleared the mark, leaving very few votes allocated for redistribution.
Serbia's Socialist Party (SPS), the junior partner in the outgoing government coalition, came in second with 11 per cent, or 30 seats, down from 13.5 per cent and 44 seats in 2014.
The far-right Serbian Radical Party (SRS) also returns to parliament, forming the opposition to Serbia's EU membership after a two-year hiatus with 8 per cent of the vote, or 21 seats.
Both the Democratic Party (DS) and a newcomer reformist group called Enough collected 6 per cent and 16 seats, while a further 10 seats go to ethnic minorities.
The far-right Dveri movement is set to enter parliament for the first time after winning 5 per cent of the votes and 13 seats, claiming the same amount as a Democrats splinter party led by former Serbian president Boris Tadic.
The tally for Dveri was reportedly less than 50 votes over the 5-per-cent threshold.
A repeat vote with less ballots for Dveri or the Democrats splinter party could easily see the two losing their place in parliament and their seats being redistributed among the winning parties.
As a result, the SNS stands to extend its lead by six or seven seats if Dveri is eliminated and as much as 13 if Tadic is also forced out.
Both the opposition and SNS filed complaints alleging violations after Sunday's elections.
Vucic had called the elections two years ahead of their scheduled date. The prime minister said he wanted a full four-year term to deal with EU membership talks and reforms.
The deadline for the parliament to convene is one month after the elections. Repeat polling, presumably on May 4, may delay the result by as much as two weeks, state TV RTS reported.