The Libyan National Army of commander Khalifa Haftar rejected on Friday the deployment of any foreign forces in southern Libya to combat the flow of migration.
The LNA said any attempt by "foreign parties to deploy a military presence in some areas of southern Libya on the pretext of stemming illegal migrations" is rejected.
"The army's general command warns these foreign parties that any such (military) deployment would be considered a flagrant violation of international law and a heinous aggression against Libyan sovereignty," a statement said.
It added that the LNA would take "all the necessary measures to protect Libya and its borders", without elaborating.
It issued its stance after European Union leaders struck a deal to deter Mediterranean crossings.
The bloc's leaders agreed to consider setting up "disembarkation platforms" outside Europe, most likely in North Africa, to discourage migrants from boarding EU-bound boats.
On Monday, the Tripoli-based Government of National Accord Vice President Ahmed Maiteeq said that the UN-backed government "categorically refuses" the installation of migrant centers in Libya.
Maiteeq made the remarks during a visit to Tripoli by Italy's new far-right Interior Minister Matteo Salvini.
During the visit Salvini had called for processing centers to be set up "south of Libya, on the external border of Libya" as a way to block attempts by migrants to head for Europe and "to help Libya as well".
Haftar's forces control much of eastern Libya and some regions in the country's south.
Earlier on Friday, around 100 people are thought to have drowned from a migrant boat off Libya’s western coast after their boat capsized off the coast of the North African country, a coastguard official said.
The coastguard picked up 14 survivors from the boat just east of the capital, Tripoli, the official said.
Separately, the coastguard said it had intercepted 200 migrants from two other migrant boats east of Tripoli.
The Libyans managed to rescue 14 migrants from the group, The Associated Press quoted coast guard's spokesman Ayoub Gassim as saying. He could not provide definitive numbers for the migrants who were on board or their nationalities.
The boat capsized east of the Libyan capital, Tripoli, and the 14 were rescued early on Friday, he added. It was unclear when they embarked on the perilous trip for Europe or from where they had set off.
