The incumbent pro-EU populists have dominated Serbia's parliamentary election, leaving pro-Russia nationalists far behind, initial unofficial results show.

The apparent triumph by prime minister Aleksandar Vucic's Progressive Party means Serbia will continue on its path toward European Union membership despite opposition from right-wing parties, which sought close ties with Russia instead.

The preliminary results published on Sunday by the Cesid independent pollster agency say that the Progressives won 52% of the vote while their coalition partner the Socialists had 14%.

The ultra-nationalist Radical Party had 7%, followed by pro-Western Democratic Party with 5%.

Djordje Vulkovic from Cesid said there might be slight changes from those partial results, but what is clear is that there cannot be changes in the first two parties.