Over 30,000 refugees and migrants have arrived in Yemen this yearListen /
More than 500 Ethiopian migrants, including women and children, were recently freed from houses run by human traffickers in Yemen, according to the UN refugee agency, UNHCR.
Many of those released showed signs of torture and abuse.
UNHCR says although Yemeni authorities have been conducting similar raids over the past year, incidents of extortion, exploitation, violence and sexual abuse perpetrated against refugees, asylum seekers and migrants are on the increase in the region.
Adrian Edwards from UNHCR, says despite the harrowing ill- treatment of migrants and refugees in Yemen, many others were still willing to take the perilous journey across the Gulf of Aden.
This year alone, more than 33,000 African migrants arrived in Yemen.
"Most are Ethiopian nationals, with the rest coming from Somalia and a very small number from other African countries. Conflict and instability in Yemen have limited the ability of the authorities to address trafficking, particularly along the Red Sea coast where Yemeni smugglers and traffickers are often waiting to receive new arrivals from the Horn of Africa."
Yemen is frequently used as a transit point by Ethiopians and Somalis trying to travel to the Gulf States and beyond.
The country hosts more than 242,000 refugees.
Patrick Maigua, United Nations Radio, Geneva