Serbian police have arrested 15 people suspected of trafficking more than 200 migrants from Syria, Afghanistan and Pakistan toward the European Union.

The police said Monday the alleged criminal group smuggled migrants over the border from Bulgaria and crossed them through Serbia aiming to reach Hungary, an EU member. Each migrant was charged 1,000 euros ($1,084) for the trip.

Serbia and the rest of the Balkans have become one of the main transit routes for migrants seeking to reach the 28-nation EU. Officials say people from Africa and Asia most often are trafficked from Greece or Bulgaria north to Hungary.

Rights groups have accused Serbia of harassing migrants who are fleeing wars and poverty.

Serbia has pledged to curb human trafficking as it seeks to become an EU member.