TRIPOLI, Libya — A court in Libya on Tuesday sentenced a son of Moammar Gadhafi to death by firing squad after convicting him of murder and inciting genocide during the 2011 uprising.

The Tripoli court that sentenced Seif al-Islam, who is being held by a militia that refuses to hand him over, also sentenced to death eight others, including former Libyan spy chief Abdullah al-Senoussi, who is in government custody.

It was unclear whether the sentences in the mass trial of 38 Gadhafi-era figures, only 29 of whom were present, would be carried out. Six others were sentenced to life in prison and four were cleared of charges.

U.S.-based Human Rights Watch said the trial was "undermined by serious due process violations," and called on the Supreme Court to independently review the verdict.

"This trial has been plagued by persistent, credible allegations of fair trial breaches that warrant independent and impartial judicial review," said Joe Stork, deputy Middle East and North Africa director. "The victims of the serious crimes committed during the 2011 uprising deserve justice, but that can only be delivered through fair and transparent proceedings."

Libya has slid into chaos since the overthrow and killing of Gadhafi, who ruled the country for four decades. It is now bitterly divided between an elected parliament and government cornered in the country's east, with little power on the ground, and an Islamist militia-backed government in the west that has seized the capital, Tripoli.

Since the end of the civil war, Seif al-Islam has been held by a militia in Zintan, which is allied with the Tobruk-based internationally recognized government against the Tripoli one. The court that convicted him is affiliated with the Tripoli-based government. He is also wanted by the International Criminal Court in The Hague on charges of crimes against humanity.

During the trial, Seif al-Islam was accused of recruiting mercenaries who were given Libyan nationality, planning and carrying out attacks on civilian targets from the air, forming armed groups and shooting into crowds of demonstrators. Among the charges he was convicted of were incitement of murder and rape.

Hundreds of militias in Libya are battling for power and turf in a lawless environment has allowed human traffickers and kidnappers to flourish.

The U.N. envoy for Libya, meanwhile, has urged the Islamist-led government in Tripoli to sign a peace deal that would establish a unity government. Members of the Tobruk government and regional leaders signed the unity accord in Morocco on July 11.

Also sentenced to death on Tuesday were foreign intelligence chief Abu-Zeid Omar-Dawarda and Gadhafi's former Prime Minister Baghdadi al-Mahmoudi.

The New York Times