The fast increasing deployment of forces could potentially result in significant population displacement, the report said.
Libya has been mired in chaos since the ouster and killing of dictator Moamer Qadhafi in 2011, with two rival authorities and a multitude of militias vying for control of the oil-rich country.
The United States called on Sunday for an immediate halt to military operations in Libya as the Libyan National Army headed by Khalifa Haftar advanced on the capital, Tripoli.
The US on Sunday appealed for an "immediate halt" to a military offensive by Libyan strongman Khalifa Haftar, as fighting raged near Tripoli despite a UN call for a ceasefire.
At least 264 people have been killed and 1,266 wounded, including civilians, in an offensive by military strongman Khalifa Haftar to seize Libya’s capital Tripoli, the World Health Organisation (WHO) said on Tuesday.
A self-styled Libyan army slowed down its push on the country’s capital over concerns for civilians caught up in the violence as the UN refugee agency said on Monday that the fighting for Tripoli has displaced more than 32,000 people.
The UN chief warned Libya is on the brink of “a very dangerous situation” as forces loyal to the internationally recognised government and a rival commander battle for control of the capital.
"Thousands of people have fled their homes, while others are trapped in conflict areas. Hospitals inside and outside (Tripoli) are receiving daily casualties," the United Nations health agency said in a statement.
Eastern Libyan forces bogged down in street battles in a push to seize the capital Tripoli deployed warplanes on Friday to hit two government positions as more civilians fled fighting. The Libyan National Army (LNA) force of Khalifa Haftar advanced on the coastal city of about 1.2 million people a week ago in the latest conflict of a cycle of anarchy since the 2011 overthrow of dictator Muammer Qadhafi.
The World Health Organisation (WHO) said on Friday that it feared outbreaks of infectious diseases due to dirty water and people fleeing fighting nearing Tripoli, where it has about two weeks of emergency supplies for hospitals and health facilities.