[Afghan migrants who live in the Hellenikon refugee and migrant camp of Athens register for asylum on Monday, June 13, 2016. Authorities began registering applications at the site Monday, in a processes expected to last months as more than 50,000 migrants and refugees have been stranded in Greece in the wake of European border closures. (AP Photo/Petros Giannakouris)]THESSALONIKI, Greece (AP) — Police detained 34 volunteers in northern Greece Monday while clearing makeshift migrant camps along the border with Macedonia.