A spokesman for Libya's powerful paramilitary based in the eastern city of Benghazi says its troops are launching an operation "to cleanse" the country's south of Islamic militants and criminals.
Ahmed Al Mesmari of the self-styled Libyan National Army that answers to Field Marshal Khalifa Haftar told reporters on Tuesday that the operations aims to "eliminate gangs, Islamic State terrorists and criminals" in the south.
He says the operation will also try and stem illegal migrants from sub-Saharan Africa, describing it as an "international problem."
The UN recently deplored deteriorating security in southern Libya.
Libya slid into chaos after the 2011 uprising that overthrew and killed long-ruling dictator Muammar Qaddafi . The country is currently governed by rival authorities in Tripoli and the east, each backed by an array of militias.