Bulgarian Police, on Monday stopped a truck carrying 15 migrants from Syria, Iraq and Afghanistan in its refrigerated trailer and arrested the two Greek drivers.
The Interior Ministry in Sofia said that the lorry, Hungary bound, had arrived from Greece and was intercepted at Vidin, on the border with Romania.
In spite several countries along the Balkan route closing their borders at the height of the migration crisis four years ago, migrants continued to use the route to try to reach wealthier European countries.
After more than one million migrants passed along the route in just over 10 months in 2015-16, the borders were shut to curb flow of people fleeing conflict and economic hardship and gaining access to EU states without thorough checks.
Migrants frequently pay smugglers to transport them across the countries and through the borders, often risking their lives.
In Aug. 2015, 71 people suffocated in a lorry similar to the one stopped in Bulgaria, as they were driven through Hungary and into Austria.