Updated

The U.N. says rockets and mortar shells have reportedly been fired on residential neighborhoods of Libya's capital Tripoli, where heavy fighting has led to a deteriorating humanitarian situation.

U.N. spokesman Stephane Dujarric said Friday that the U.N. is "gravely concerned" at reports of indiscriminate shelling of populated areas, including Thursday night.

Forces loyal to Field Marshal Khalifa Hifter launched an offensive on Tripoli earlier this month and are battling militias loosely allied with the U.N.-supported government.

Dujarric said nearly 39,000 people have been displaced by the fighting, according to the International Organization for Migration.

He says: "Civilians in conflict-affected areas are experiencing electricity cuts and water shortages as a result of damaged infrastructure, while access to essential items such as food, medicine and fuel is severely disrupted."