The UN Security Council urged Libya's warring parties Friday to immediately commit to a cease-fire and return to UN-brokered peace talks.

Indonesia's UN Ambassador Dian Triansyah Djani, who is president of the 15-member body for the month, made the appeal on behalf of the Council, stressing it is "deeply concerned" by instability in Tripoli and spiraling humanitarian situation.

In early April, renegade military commander Khalifa Haftar, who commands forces loyal to a rival government based in eastern Libya, launched a wide-ranging campaign to seize the capital from the UN-recognized government.

After more than a month of sporadic fighting on Tripoli’s outskirts, however, Haftar's campaign has failed to achieve its primary objective.

Haftar’s forces have managed to surround the city of Zuwara, located 60 miles (100 kilometers) west of Tripoli, from the east and south. Zuwara is of considerable strategic importance as it controls the Ras Ajdir border crossing with Tunisia.

Haftar has also succeeded in taking Garyan, located 60 miles south of Tripoli, allowing his forces to cut the desert road linking Tripoli to the Dehiba Wazin crossing.

Libya has remained beset by turmoil since 2011, when long-time leader Muammar Gaddafi was ousted and killed in a bloody NATO-backed uprising after four decades in power.

The oil-rich country has since seen the emergence of two rival seats of power: one in eastern Libya, with which Haftar is affiliated, and another in Tripoli, which enjoys UN recognition.