[Children play at the top of a tent at Ritsona refugee camp north of Athens, which hosts about 600 refugees and migrants on Thursday, Sept. 8, 2016. The refugee crisis is expected to be a central issue in discussions Friday at a meeting in Athens of leaders from Mediterranean countries in the European Union. (AP Photo/Petros Giannakouris)]ATHENS, Greece (AP) — Refugee and migrant children in Greece are being held in police cells, often in "poor and degrading conditions" due to a lack of appropriate shelter space, Human Rights Watch said in a report published Friday.