Serbia's prime minister has met with Russian President Vladimir Putin in Moscow amid reports that the Kremlin is worried about the Balkan country's attempts to join the European Union and other Western organizations like NATO.

The unannounced visit by Aleksandar Vucic on Thursday resulted in calls by Moscow to "include people who are determined to maintain and strengthen further relations between Serbia and Russia" in the new government.

Vucic's populist Serbian Progressive Party has won a majority in parliament in April elections, but there were reports that their coalition partners, the Socialists — a staunchly pro-Putin party — won't be included in the next government.

Serbia, a traditional Russian ally, has been deeply split among those seeking EU membership and those who prefer a close union with Russia instead.