Algeria's interior ministry on Friday defended moves to expel dozens of migrants as a matter of "national security", after the UN voiced concern over a group who went missing in the desert.
The global body's refugee agency UNHCR said Thursday that 100 people were "unaccounted for" after being taken to the border, while 20 others remained "stranded in the desert".
It said the group of Syrians, Palestinians and Yemenis had been detained in southern Algeria before being taken to an area near the Guezzam border post on December 26.
Hacen Kacimi, an Algeria interior ministry official, said the expulsions took place after legal decisions "closely linked to national security priorities".
"No party, irrespective of its status, can interfere in the execution of a judicial decision," he added.
Mr Kacimi, who heads the ministry's migration department, had previously said the migrants entered Algeria illegally and were put on trial in September.
His comments came after the Algerian League for the Defence of Human Rights on Monday denounced the deportation to Niger of 50 mostly Syrian migrants, including women and children, who were smuggled into the country in September.
Algeria does not have asylum legislation and the official said many of the migrants – mostly Syrians from Aleppo – were suspected of having ties to militant groups.
Mr Kacimi on Friday accused UNHCR of "erratically" registering asylum applications, after the agency said some of those expelled were registered refugees.
Defending the expulsion at the remote desert border, Mr Kacimi said the group "refused to be repatriated by air".
Human rights organisations regularly criticise Algeria for its treatment of migrants, many of whom come from sub-Saharan Africa in the hope of reaching Europe.
The UN in October urged Algeria to stop collective expulsions of migrants across its Niger border, after rights groups accused authorities of rounding up thousands of people and expelling them into the desert.
Algeria has faced an influx of sub-Saharan migrants with rights groups estimating some 100,000 have entered the country in recent years.
A portion of those have tried to make the journey to Europe or travelled elsewhere in North Africa to attempt that trip. The number of people illegally crossing into Europe dropped last year to its lowest level in five years. A total of around 150,000 entered the EU through irregular entry in 2018, coastguard agency Frontex said. The drop was primarily caused by a fall in the number of migrants attempts trips from Algeria, Tunisia or Libya en route to Italy.