Serbia's ruling populists, who won last week's election by a landslide, have demanded a vote recount after several smaller opposition parties made it to Parliament.

The pro-EU Serbian Progressive Party won 48 percent of the seats in the 250-seat Parliament. That is 27 seats fewer than in the previous general vote in 2014.

The official tally also shows pro-Russian nationalists winning seats in the legislature, as well as three pro-Western groups which marginally passed the 5 percent threshold to enter Parliament.

Incumbent Prime Minister Aleksandar Vucic, who is accused by the opposition of seeking an authoritarian rule, said Tuesday "strange things happened" during the vote count on Sunday.

Opposition parties have also claimed numerous irregularities during the vote and have formed a body to investigate.