Forces loyal to Libya's renegade General Khalifa Haftar are marching on the capital, Tripoli, igniting fears of renewed war in the chaos-wracked country.

Axar.az reports citing AlJazeera.

The assault by Haftar's self-proclaimed Libyan National Army (LNA) raised fears of a full-blown battle in Tripoli, the seat of a United Nations-backed government that is protected by an array of militias holding sway over the city's economy and institutions.

Following Haftar's move on Thursday, the Tripoli-allied militias mobilized for "war" by deploying troops and moving weapons from the coastal towns of Misrata and Zawiya to areas around the capital.

As skirmishes broke out near Tripoli on Friday, Antonio Guterres, the UN chief who was in the capital to help organize a conference aimed at hammering out a roadmap for elections, headed to the eastern city of Benghazi to meet Haftar.

But he wrote on Twitter later in the day: "I leave Libya with a heavy heart and deeply concerned. I still hope it is possible to avoid a bloody confrontation in and around Tripoli."

The escalation threatens to undermine UN-led efforts to bring stability to a country that has for years been split between the internationally recognized Government of National Accord (GNA) in Tripoli and a rival administration in the east allied to Haftar.

The 75-year-old former army officer's rise, including advances on strategic oil fields and port cities, has come on the back of support by countries such as neighboring Egypt and the United Arab Emirates. He has portrayed himself as the only solution for Libya's instability, but many in the country fear he could try to reinstate authoritarian rule.