The battle for Libya's capital intensified as the UN Security Council prepared to meet Wednesday to discuss the crisis gripping the North African country, where armed rivals are locked in a deadly power struggle.

The closed-door talks in New York come a day after the United Nations postponed a Libyan national conference aimed at drawing up an election roadmap because of fighting raging on Tripoli's doorstep.

Russia has said it is not taking sides in the fighting in Libya but behind the scenes, experts say, Moscow is firmly backing strongman Khalifa Haftar.

Russia on Sunday blocked a U.N. Security Council statement that would have called on forces loyal to Libyan commander Khalifa Haftar to halt their advance on Tripoli, diplomats said.

At least 32 people have been killed and around 50 wounded in fighting with strongman Khalifa Haftar's troops near Tripoli, the UN-backed government said.

The head of Libya's U.N.-backed government Fayez al-Sarraj has accused his rival Khalifa Haftar of betraying him over a military offensive against the capital Tripoli which risks plunging the country into civil war.

The UN Security Council on Friday called on Libyan forces under Khalifa Haftar to halt their advance on Tripoli, warning the military move was putting Libya's stability at risk.

Russia expressed hope Friday that the crisis in Libya would not lead to "renewed bloodshed", adding that Moscow did not support Libyan strongman Khalifa Haftar.  

The US envoy tasked with forging a peace deal with the Taliban met with officials in Pakistan on Friday, after telling leaders and various groups in Afghanistan they would be included in future talks.

Forces loyal to Libyan strongman Khalifa Haftar were pushed back Friday from a key checkpoint less than 30 kilometres from Tripoli, checking their lightning advance on the capital, a security source said.

Libya has been mired in chaos since the ouster and killing of dictator Moamer Kadhafi in 2011, with two rival authorities and a multitude of militias vying for control of the oil-rich country.