The UN on Tuesday called for a probe into a fire that killed dozens of migrants at a holding facility in Yemen's capital, after Human Rights Watch said it was started by Huthi rebels.
The rights group said the detainees -- most of them Ethiopian -- had been protesting against overcrowding on March 7 when camp guards rounded up hundreds of them in a hangar.
They then fired "unidentified projectiles" into the building, it said.
Footage of the aftermath, which AFP obtained from a survivor, showed dozens of charred bodies piled on top of one another and strewn across the ground. One person was heard crying out in prayer.
The United Nations' envoy for Yemen, Martin Griffiths, told the Security Council Tuesday that "there must be an independent investigation into the cause of the fire".
He said dozens had died and over 170 seriously injured.
Griffiths said the "extraordinary, horrific fire" had reminded the world "of the plight of the migrant community".
The Iran-backed Huthi rebels control much of northern Yemen, including the capital Sanaa, whose capture from the Saudi-backed government in 2014 sparked a devastating war.
Despite warnings from civil society groups, migrants from the nearby Horn of Africa continue to transit through the war-torn and impoverished country, seeking a better life in the wealthy neighbouring Gulf Arab states.
- 'I was terrified' -
Human Rights Watch said Huthi security forces had locked the migrants in the building after a "skirmish" between guards and detainees. Citing migrant witnesses, it said the militants had then launched two unidentified projectiles into the building.
"The migrants said the first projectile produced a lot of smoke and made their eyes water and sting. The second, which the migrants called a 'bomb', exploded loudly and started a fire," it said in a report.
A video published by HRW showed security forces walking among survivors outside the facility as the fire raged inside, sending black smoke billowing into the sky.
"I don't have the words to express what it was like -- (the projectiles) exploded, and there was so much smoke and then there was a fire that spread," HRW quoted a 20-year-old migrant as saying.
"I was terrified, I felt like my mind was blocked with smoke."
HRW said hundreds of injured migrants were being treated in hospitals in Sanaa where a "heavy security presence" had posed problems for humanitarian agencies trying to reach them.
The rights group cited interviewees saying they had seen the Huthis re-arrest migrants who were not severely injured.
It urged the Huthis to "urgently engage with Ethiopian authorities whose nationals are languishing in Yemeni detention centres under their control".
- Migrants repatriated -
Ethiopia's foreign ministry said it had received reports of 43 people, including many Ethiopian nationals, dying in the fire and being buried in Yemen.
"Our embassy based in neighbouring Oman is working with the likes of IOM, UNHCR (United Nations High Commissioner for Refugees) and the Red Cross to know the fate of our citizens in Yemen," ministry spokesman Dina Mufti told a press conference.
Meanwhile, the International Organization for Migration (IOM) said that 140 Ethiopians had arrived in Addis Ababa from the Yemen government-controlled southern city of Aden on Tuesday, the first flight it has facilitated since the outbreak of the coronavirus pandemic.
"This flight is a vital lifeline for migrants who have been stranded for months on end in unsafe conditions," IOM's director general Antonio Vitorino said in a statement.
"In the coming months, we hope to see more migrants able to safely go home to their loved ones in this way."
The IOM last week urged the Huthi rebels to provide unimpeded access to those injured in the Sanaa fire.
In correspondence with HRW, Huthi spokesman Mohammed Abdulsalam said the incident "should not be politicised or exploited".
"The incident that took place was a normal result that occurs in similar incidents all over the world," he reportedly said.
Abdulsalam called for the lifting of a longstanding Saudi-led blockade on Sanaa's rebel-controlled airport, so migrants "can return home".