Bosnian border guards have stopped dozens of migrants seeking to cross into European Union member Croatia.
The June 18 incident in northwestern Bosnia came amid a sharp increase in migrants from the Middle East, Africa, and Asia seeking refuge in Western Europe.
About 100 migrants had moved toward from the town of Velika Kladusa, where hundreds have been staying in makeshift camps, to the Maljevac border crossing, but police blocked them from proceeding.
Many then staged a sit-in on the access road as police tried to persuade them to turn back.
Peter Van der Auweraert, an official with the International Organization for Migration, posted a video to Twitter showing the standoff and wrote that the police move was a "very worrying development that risks" creating a backlash.
Emina Buzinkic, a Croatian migration activist, told RFE/RL that some migrants had managed to cross earlier, but Croatian police refused to receive their asylum applications. She said some were roughed up by police and had their cell phones destroyed or money stolen.
Sanela Dujkovic, a spokeswoman for the Bosnia-Herzegovina border police, told RFE/RL that the border crossing was functioning normally but could only be reached via a secondary route.
In recent months, migrants have turned to Bosnia in order to avoid other routes through the Balkans, many of which are more heavily guarded.