UNITED NATIONS (AP) — The chief prosecutor of the International Criminal Court reported Tuesday that the recent failed offensive by Libya’s eastern-based forces involved a pattern of violence and the use of mines by retreating forces that harmed civilians, which is a war crime when used indiscriminately.

Fatou Bensouda said “credible information” on the increasing use of mines and improvised explosive devices against civilians was discovered when people who fled the fighting returned and “were either killed or injured because their homes were booby trapped by such devices.” At least 49 people were killed by mines just between April and June, she told the U.N. Security Council.

Bensouda said the latest information indicated the offensive by eastern forces under military commander Khalifa Hifter formed part of “a pattern of violence that involves the indiscriminate airstrikes and shelling of civilian areas; arbitrary abduction; detention and torture of civilians; extrajudicial killings; enforced disappearances; and pillaging of civilian property.”

She said this repeated a pattern of violence previously reported in places such as Hifter’s base in the main eastern city of Benghazi, the former Islamic State extremist stronghold of Derna that his forces recaptured in 2019, and Ajdabiya in the east, Marzuq in the south and the coastal city of Sirte that Hifter also controlled.

Bensouda said that since the discovery of mass graves in June in Tarhuna, which Hifter’s forces used as a base to launch their attack in April 2019 seeking to take the capital of Tripoli, over 100 bodies have been found, many blindfolded and with their hands tied. She said in the virtual briefing that her office is engaging with the U.N.-recognized government in Tripoli “in relation to these mass graves.”

Libya has been in turmoil since 2011, when a NATO-backed uprising toppled long-time dictator Moammar Gadhafi, who was later killed. The country has since split between rival administrations in the east and the west, each backed by armed groups and foreign governments.

Hifter’s offensive, supported by Egypt, the United Arab Emirates and Russia, collapsed in June when militias backing the Tripoli government, with support from Turkey, gained the upper hand.

Bensouda welcomed the Oct. 23 cease-fire agreement between the warring parties and urged its implementation to “usher in the much awaited peace and stability for the people of Libya."

She also stressed the importance of justice and accountability.

“Victims of atrocity crimes in Libya must be reassured that notwithstanding any cease-fire or future agreement, individuals alleged to be responsible for serious crimes falling under the jurisdiction of the International Criminal Court will be promptly arrested and surrendered to the court to face charges for their alleged crimes,” she said. Those include war crimes, crimes against humanity and genocide.

Bensouda noted that the U.N. political mission in Libya recently called for an investigation into the alleged use of excessive force by security forces on Aug. 23 in Tripoli and Zawiya, a coastal town about 30 miles (48 kilometers) west of the capital.

The ICC also continues to receive information about “allegations of serious crimes being committed in prisons and detention facilities throughout Libya,” the prosecutor said, citing the Kuweifiya and Gernada facilities in the east and Mitiga Prison in Tripoli. She added that the court also continues to receive evidence of allegations of torture and the arbitrary detention of civilians “under inhumane conditions” at those facilities.

“I urge all parties to the conflict in Libya to immediately put an end to the use of detention facilities to mistreat and commit crimes against civilians,” Bensouda said, stressing that international law and the Rome Statute that established the ICC prohibit the use of detention facilities in this way.

She also called for international observers and investigators to be given full access to detention facilities in Libya.

In addition to detainees, Bensouda said, her office has been monitoring “the situation of internally displaced persons as well as crimes committed against migrants” who continued to be trafficked and subjected to crimes including torture.

She expressed deep concern that Ahmad Oumar Al-Dabbashi, who is on the U.N sanctions blacklist for crimes against migrants, is reportedly continuing the same crimes.

Bensouda said recent “positive developments” toward eradicating crimes against migrants are encouraging and urged intensified efforts to protect migrants.

The ICC prosecutor again decried the failure to arrest Libyans sought by the court -- especially Seif al-Islam Gadhafi, the late dictator’s son; Mahmoud al-Werfalli, a commander in Hifter’s forces; and Al-Tuhamy Mohamed Khaled, former head of the Libyan Internal Security Agency.

Bensouda called for intensified efforts to arrest al-Werfalli, “who as a commander of Al-Saiqa Brigade, is alleged to have executed 43 civilians,” and Al-Tuhamy, who is reportedly living in Egypt and should be arrested by the government.