UN envoy Ghassan Salame has bitterly denounced the conflict in Libya saying it is "committing suicide" and plundering its oil wealth to pay for the war.

After years of assassinations, bombings and militia firefights, Libya's eastern city of Benghazi finally feels safe again — but security has come at a heavy cost.

Uniformed police are out at major intersections, cafes and restaurants stay open late into the night, and local groups hold art exhibitions and festivals. But the city center lies in ruins, thousands remain displaced, and forces loyal to commander Khalifa Hifter, who now controls eastern Libya, have cracked down on dissent.

Peering through the gate of a home in the western suburbs of Libya's war-torn capital, seven-year-old Chehab shyly looked on as children streamed down the nearby street.

Peering through the gate of a home in the western suburbs of Libya's war-torn capital, seven-year-old Chehab shyly looked on as children streamed down the nearby street.

The battle for Tripoli between rival Libyan forces both championing the fight against "terrorism" has created a security vacuum, allowing the Islamic State group a chance to re-emerge, analysts warn.

Libya expert Emad Badi says the fighting has given IS "the opportunity to reorganise, recruit and strike alliances with other groups (and organise attacks) to show they are still around".

The UN Security Council will meet behind closed doors to discuss the humanitarian crisis in Libya as a month-long offensive on the capital grinds on, diplomats said on Thursday.

Libyan strongman Khalifa Haftar, who launched an offensive against Tripoli last month, urged his troops to inflict "an even harder" lesson on forces loyal to the country's internationally recognised government.

Air raids on Tripoli Sunday night killed four people and wounded 37, Libya's Government of National Accord (GNA) said Monday, blaming the attacks on strongman Khalifa Haftar's self-styled Libyan National Army (LNA).

Fierce fighting for control of Libya's capital that has already displaced tens of thousands of people threatens to bring a further worsening of humanitarian conditions, a senior UN official has warned.

Intensified fighting for control of the Libyan capital is turning residential areas of Tripoli into "battlefields", the International Committee of the Red Cross said Thursday.