Serbian authorities have arrested five people suspected of trafficking more than 140 migrants.
The detainees are accused of helping migrants cross into neighboring Bosnia-Herzegovina, prosecutors said on February 19.
"Since November of last year, a group of suspects smuggled migrants by bus from Belgrade to the border with Bosnia-Herzegovina," the prosecutors’ statement said.
Led by a Syrian national, the group also used boats to cross the Drina River to reach Bosnia.
One suspect is at large, and authorities said the group was paid some 17,000 euros ($18,000) for their activities.
Once in Bosnia, migrants try to enter Croatia, a member of the European Union.
Some 29,000 migrants entered Bosnia last year, according to the Bosnian government.
Many are fleeing war and poverty in their home countries and have been stranded in Serbia and other Balkan countries as they seek to enter Europe’s more developed countries.
Officials say most of the migrants come from war-torn countries like Syria, Iraq, Afghanistan, and Yemen.