TRIPOLI — Thirteen people were killed in a second day of clashes between Libyan soldiers and tribesmen in the remote southeast, a security official said, highlighting the challenges the new government still faces in imposing its authority.

Violence erupted in the early hours of Saturday in the city of Al Kufra, near Libya’s borders with Chad and Sudan, where armed forces were sent in February to quell fighting in a long-standing rivalry between the Tibu and Zwai tribes.

Bouts of violence in the southern Sahara and in the mountainous west have shown how volatile Libya remains following last year’s demise of Muammar Gaddafi, who had long played off one tribe or clan against the other to weaken their power. — Reuters