Over 500 people have been killed and more than 2,400 have been wounded so far in the conflict, according to the World Health Organisation
Libyan Field Marshal Khalifa Haftar called for the disarmament of militias defending the capital before he would agree to stop his offensive on Tripoli, promising gunmen who lay down their arms would be "safe and sound".
Field Marshal Haftar said his forces had begun their march on Tripoli after six rounds of failed negotiations with the United Nations-recognised government led by Prime Minister Fayez Al Sarraj, according to an interview published in France's Journal du Dimanche.
“Of course, a political solution remains the objective," Field Marshal Haftar was quoted as saying. "But to get back to politics, we have to finish with the militias once and for all.”
He offered amnesty to fighters in Tripoli disarmed, saying they would be allowed to "return home safe and sound".
During an international trip last week, Field Marshal Haftar told French President Emmanuel Macron that he was willing to negotiate a ceasefire but conditions were not right.
Field Marshal Haftar's forces, the Libya National Army, began an offensive on Tripoli nearly two months ago but has yet to breach the city. A new push to crack the capital's southern defences began on May 25. At the start of May, the LNA leader called on his men to fight harder during Ramadan.
Field Marshal Haftar also said in the interview that United Nations special envoy Ghassan Salame was no longer impartial.
In an address to the Security Council, Mr Salame urged the body to take more action to stem the flow of arms that has fuelled the fighting in what he claimed was shaping up to be the "start of a long and bloody war".
“Without a robust enforcement mechanism, the arms embargo into Libya will become a cynical joke. Some nations are fueling this bloody conflict; the United Nations should put an end to it,” Mr Salame told the Security Council.
Libya has been subject to a UN arms embargo since 2011 but several countries are believed to have supplied weapons, including recently Turkey who appeared to deliver at least a dozen armoured personnel carriers. Images of the new vehicles were shared on the official Facebook page for the defensive operation to defend the capital.
"Salame is making irresponsible statements," Field Marshal Haftar said. "He wasn't like that before, he has changed. From an impartial and honest mediator, he has become a biased one."
The North African country has been unstable since the 2011 uprising and subsequent overthrow and execution of then leader Muammar Qaddafi. Since then the country has been divided by two competing governments. Mr Sarraj's internationally-recognised government is based out of Tripoli while Field Marshal Haftar's influence is centred in the East. Dozens of militias are also active players in the conflict.
Some 510 people have been killed and more than 2,400 have been wounded in the fighting, according to the World Health Organisation.
The clashes between Field Marshal Haftar and Mr Sarraj's military forces have driven 75,000 people from their homes and trapped nearly 100,000 people on the outskirts of Tripoli.