CAIRO - Armed groups loyal to Libya's self-styled national army may have killed dozens of civilian men in a town some 50 kilometres (30 miles) east of Benghazi, Human Rights Watch said Wednesday.

In a detailed report, the U.S.-based watchdog said the bodies of 36 men were found on Oct. 26, near the town of al-Abyar.

It said about 23 victims had their hands tied behind their backs with plastic handcuffs, and the majority had visible gunshot wounds to the head, neck or face.

At the time of the discovery, spokesman Awad Aladouli of the eastern interim government's Ministry of Interior said the dead, apparently of different ages and socio-economic backgrounds, were found in attire ranging from athletic wear to business suits. Some victims had been shot in the head.

Hifter is loyal to the interim government. Another, United Nations-backed government is based in Tripoli.

Phone calls and a message left with a spokesman for Hifter were not immediately returned.

HRW said relatives of six victims say the men had been arrested earlier in 2017 in Benghazi or other areas controlled by forces led by Field Marshal Khalifa Hifter who commands the self-styled Libyan National Army.

The relatives said all six victims were civilians seized from their homes, in the presence of their families, by armed groups linked with the Hifter's force without providing an arrest warrant, it said.

In one case, Ayman el-Sahati told Human Rights Watch that a group of masked, uniformed men stormed the family home in the district of al-Laithi in Benghazi late on the night of Oct. 25. He said they detained his brother Ahmed el-Sahati, 42, who was married and had four children. "We didn't hear from Ahmed until his photo showed up among the 36 dead in al-Abyar," he told the rights group.

This incident, HRW said, comes after a series of unlawful killings in Benghazi that prompted the International Criminal Court (ICC) prosecutor to issue an arrest warrant against a special forces commander loyal to Hifter on Aug. 15.

On Nov. 9, ICC prosecutor Fatou Bensouda demanded the arrest and transfer of suspects already named in ICC warrants, including the son of former Libyan dictator Moammar Gadhafi. In the demand, she also implicated other officials as possibly being behind the al-Abyar killings, including the former head of Libya's Internal Security Agency.

Hifter ordered the military prosecutor of the eastern region to investigate the incident, but his office has yet to announce any investigation results, the group said.

"The LNA will be condoning apparent war crimes if their pledge to investigate the gruesome discovery in al-Abyar proves to be another empty promise," Eric Goldstein of Human Rights Watch said.

Libya descended into chaos following a popular 2011 uprising that toppled and killed longtime ruler Moammar Gadhafi. The oil-rich North African nation has three rival administrations, but a multitude of militias hold actual power on the ground.

News from © The Associated Press, 2017