At least eight Africa migrants have died in makeshift camps in war-hit Yemen, the UN's migration agency said Thursday, warning thousands were living under "inhumane conditions".
The International Organization for Migration said they had died of complications related to acute watery diarrhea at the Ibn Khaldoon Hospital in Lahj, a southern district controlled by the Yemeni government in its war with northern rebels.
The IOM said it learned of the deaths on Wednesday. Most were Ethiopian.
"I am deeply saddened by the deaths of these eight migrants, who were among the thousands of migrants being held in deplorable conditions across Yemen," said Mohammed Abdiker, the IOM's director of operations and emergencies.
"We have decried this policy to the authorities, urging them to take a humane approach to irregular migration."
Abdiker said the IOM had evidence guards had fired on migrants at a sports stadium in Aden, bastion of the embattled Yemeni government, wounding two and leaving a teenage boy "likely paralysed for life".
"IOM stands ready to support Yemen and other regional partners to identify sustainable responses to irregular migration, which do not involve the shortsighted abuse of vulnerable migrants and fully respects international law," he said.
"I am greatly concerned that this dire situation will further deteriorate."
Yemen has descended into chaos in the past four years of conflict, with both the Iran-linked Huthi rebels and a rival pro-government military alliance led by Saudi Arabia accused of acts that could amount to war crimes.
But the country remains on an established route for migrants from the Horn of Africa, who typically first travel by land through Djibouti before eventually undergoing perilous boat journeys across the Gulf of Aden to Yemen.
Many say they aim to travel by land to oil-rich Saudi Arabia to find work.
But many do not even survive the journey, dying at sea or at the hands of panicked smugglers.
The IOM said an estimated 5,000 African migrants, mostly Ethiopian and some from Somalia, were currently being held in makeshift camps in the government strongholds of Lahj, Abyan and Aden.
More than 1,400 people were "detained" in the Lahj camp alone, it said.
Nearly 150,000 migrants arrived in Yemen last year, according to the UN.
In January the UN announced plans to airlift some 3,000 Ethiopian migrants to their capital Addis Ababa from Yemen's Sanaa. Hundreds have already returned.
Voluntary flight returns were resumed last year after being suspended in 2015, when the Yemen war took a turn for the worse with the intervention of the regional military force led by Saudi Arabia.
Since the Saudi-led coalition intervened in the Yemen war, nearly 10,000 people have been killed, according to the World Health Organization, although other groups say the toll is significantly higher.