Yemeni authorities have rounded up about 3,000 irregular migrants, predominantly Ethiopians, in the south of the country, “creating an acute humanitarian situation,” the UN migration agency said on Friday. The International Organization for Migration (IOM) “is deeply concerned about the conditions in which the migrants are being held and is engaging with the authorities to ensure access to the detained migrants,” it said. The migrants are held in open-air football stadiums and in a military camp. The detentions began on Sunday in the city of Aden and the neighboring province of Lahj, which are under the control of the internationally recognized government backed by Saudi Arabia and the UAE, Reuters reports. Houthi rebels control Sanaa, the capital, and other major urban centers.