July 3 (UPI) -- An airstrike on a migrant center in Libya's capital early Wednesday killed at least 40 people amid a heightening conflict between the United Nations-backed Libyan transition government and its main opposition group.
The Government of National Accord blamed the leader of the rival Libyan National Army for the attack, calling it a "war crime."
"We ask the international community through the African Union, European Union and (other) organizations to take a firm and clear stance against these continued violations," the GNA said.
The Libyan army, led by Khalifa Haftar, denied it was behind the attack and implicated the GNA.
Haftar had threatened to attack targets in Tripoli after losing the strategic city of Gharyan to government forces, which slowed efforts to win control of Libya.
The U.N. refugee agency called on other nations to stop the bloodshed in Libya, which has been going since April.
"UNHCR is extremely concerned about news of airstrikes targeting Tajoura detention center East of Tripoli, and accounts of refugees and migrants deceased," the agency said Wednesday. "Civilians should never be a target."
"Civilians must not be a target [and] Libya is not a safe place of return," it added in a tweet. "States with influence must cooperate to end the conflict, rather than fuel it."
The U.N. Security Council has placed an arms embargo on Libya that lasts until at least next June, but Amnesty International said nations like Jordan, the United Arab Emirates and Turkey have ignored it to take sides in the dispute.