Hundreds of civilians in Libya have been killed in fighting since late August.

Hundreds of civilians in Libya have been killed in fighting since late August, the United Nations said on Tuesday, warning commanders of armed groups that they could face prosecution for possible war crimes including executions and torture, World Bulletin news website reported.

The North African country is struggling with fighting on several fronts as brigades of former rebels who battled side by side to oust Muammar Gaddafi in 2011 now clash for political power and a share of oil revenues.

The conflict has driven at least 120,000 people from their homes and caused a humanitarian crisis, said a joint report by the U.N. human rights office and U.N.

Support Mission in Libya (UNSMIL) that also documents shelling of civilian areas.

The toll includes an estimated 100 people killed in fighting between rival armed groups in Warshefana, near Tripoli, between late August and early October, and 170 killed in fighting in the Nafusa mountains to the southwest, it said.

Some 450 people have been killed in Benghazi since fighting escalated in mid-October. Hospitals in the city have been hit or occupied by armed groups, the report said.

At least 18 Libyan soldiers were killed and 69 others injured in clashes between forces loyal to former chief-of-staff Khalifa Haftar and militias in Benghazi, sources said Tuesday.

Adding to the chaos, Libya has had two parallel governments since August when a group called Libya Dawn seized Tripoli, forcing the internationally-recognized administration out of the capital.

"There is a serious lack of law and order, there is absolutely no accountability, so these violations are continuing with impunity, and there has been no effort to really stop that," U.N. human rights spokeswoman Ravina Shamdasani told a news briefing in Geneva on Tuesday.

"Some of these crimes may amount to war crimes," she said.

The International Criminal Court (ICC) is investigating the situation in Libya, but its chances of pursuing perpetrators are far from certain. In 12 years of operation it has secured just three convictions.