For years, the European Union has funded the Libyan Coast Guard in an effort to stop migrants and refugees arriving on its shores.
But those returned to Libya can face abuse and torture in detention camps run by the militias.
The fighting began when members of the Special Deterrence Force, which oversees some prisons in Tripoli, arrested Col. Mahmoud Hamza , leader of the 444 Brigade.
The deterrence force said that Colonel Hamza was wanted but did not publicly say why.
The tensions in Tripoli could be seen by other militias as an opportunity to try to establish a foothold in the capital.
Persons:
Col, Mahmoud Hamza, Hamza, ”, Emadeddin Badi, Abdul Hamid Dbeiba, ” — Mary Fitzgerald, Mohammed Abdusamee
Organizations:
European Union, Libyan Coast Guard, Brigade, Force, Atlantic Council, Mercy, Middle East Institute
Locations:
Libya, Tripoli, “ Tripoli, Washington