At least 17 civilians have been killed in an offensive by military strongman Khalifa Haftar's forces to take the last city in eastern Libya beyond his control, the United Nations said Friday.
"The escalation of fighting in Derna has reached unprecedented levels during the past week, with fighting further encroaching into densely populated areas," the UN Support Mission in Libya said.
"Since 16 May, at least 17 civilians, including two children, were killed and another 22, including seven children, were injured in the conduct of hostilities."
The mission called on all sides to "exercise maximum restraint" after seven civilians were killed and seven wounded by an explosion on May 30 as they were attempting to leave the city.
Haftar's self-proclaimed Libyan National Army (LNA) launched an offensive on May 7 to "liberate" the eastern coastal city, home to about 150,000 people.
Derna is controlled by a ragtag coalition of Islamist and jihadist militias, including groups close to Al-Qaeda, hostile to both Haftar and the Islamic State group.
The coalition, the Mujahedeen Shura Council, was formed to drive IS from the city in 2015, after it had taken over Derna the previous year.
Haftar's forces entered the city's suburbs last week and have tightened the noose on their opponents with the help of air strikes and heavy artillery.
LNA forces have besieged Derna for nearly two years, making it difficult for residents to access humanitarian aid.
The UN mission warned that "severe food and medicine shortages continue to worsen" and said "electricity and water are intermittently cut off".
Libya has been wracked by chaos since a 2011 uprising that toppled and killed long-time dictator Kadhafi, with two rival authorities vying for control.
Haftar supports an administration based in the east of the country and opposes a UN-backed unity government based in the capital Tripoli that has struggled to assert its authority outside the west.
Four Libyan leaders, including Haftar, agreed Tuesday to hold elections on December 10 after a peace conference in Paris aimed at unifying the war-torn north African nation.
The UN has been pushing for a nationwide polls as a key way to stabilise Libya.