Around 1,000 Ethiopian migrants escaped a detention centre in south Yemen on Wednesday with the help of their guards, a security official said.
The detainees broke out of the centre, where some 1,400 Ethiopians were being held prior to deportation after entering the country illegally, in the province of Shabwa before dawn, he said.
The getaway in the provincial capital of Ataq was "well organised", he added.
"The escapees boarded vehicles that were waiting for them to take them to the neighbouring provinces of Marib and Bayda" in small groups.
Loyalists control most of Marib except for the oil-rich Sarwah area where they are fighting the rebels, while insurgents control Bayda.
Late last month, Yemeni authorities deported at least 220 African illegal immigrants, mainly Ethiopians, from the southern port city of Aden, security officials said.
Hundreds of Ethiopians have arrived in the south of Yemen in the past months despite the conflict between loyalist forces and Shiite rebels that has gripped the country for more than 18 months.
A Saudi-led coalition intervened in Yemen in support of President Abedrabbo Mansour Hadi's government in March last year after the Iran-backed Huthis overran much of the country including the capital Sanaa.
Loyalist officials accuse the Huthis of recruiting to their ranks migrants who have entered the country illegally, but no independent source has confirmed this.
The rebels and their allies still control most of the Red Sea coast, as well as the capital and much of the central and northern highlands.
More than 6,800 people have been killed since the Saudi-led intervention began, almost two-thirds of them civilians, the United Nations says.