Secretary of State John Kerry on Monday insisted the capture of an alleged Al-Qaida operative in Libya in a U.S. raid was legal, after Tripoli demanded answers about the "kidnap".

Abu Anas al-Libi, who was indicted in connection with the 1998 bombings of U.S. embassies in Kenya and Tanzania and has a $5 million FBI bounty on his head, was captured on Saturday.

Libyans took part in the U.S. raid in Tripoli that captured senior al-Qaida operative Abu Anas al-Libi, his son said Sunday.

"Those who kidnapped my father are Libyans. They looked like Libyans and spoke in the Libyan dialect," Abdullah al-Raghi told reporters.

U.S. forces struck two militant targets in Africa on Saturday, snatching a top Al-Qaida suspect from the streets of Tripoli and launching a pre-dawn raid against a Shebab leader's home in Somalia.

In Libya, US forces seized a militant known as Abu Anas al-Libi, a long-sought Al-Qaida operative indicted in the 1998 bombings of U.S. embassies in Kenya and Tanzania.

Fifteen Libyan soldiers were killed and four wounded in an attack on an army checkpoint between two towns southeast of Tripoli, a military spokesman said.

"An army checkpoint in Al-Malti region between Tarhuna and Bani Walid was attacked at dawn on Saturday by an unknown group. Fifteen soldiers were killed and four others wounded," Ali Sheikhi said.

Before many African migrants can even begin the perilous sea crossing to Europe they must pass through Libya, where they face exploitation or arrest by often brutal militias.

The feared drowning of some 300 African asylum-seekers in a shipwreck off Italy this week has underscored the dangers that desperate migrants from Sub-Saharan Africa face as they seek a better life in Europe.

An assault on the Russian embassy in Tripoli that sparked the evacuation of its staff highlights a continued inability to protect diplomats that threatens Libya with renewed isolation, analysts say.

Wednesday evening's attack on the Russian compound triggered an exchange of fire in which two of the assailants were killed.

Two assailants were killed when protesters attacked Russia's embassy in Tripoli, a Libyan minister said Thursday, while denying Moscow's claims that it had evacuated the embassy on his request.

"Two Libyans were killed in the attack" late Wednesday, said Libyan Foreign Minister Mohamed Abdelaziz, adding that he had urged embassy staff not to spend the night in the compound for fear of a second attack.

A Tripoli court will decide October 24 whether to indict more than 20 senior figures from Moammar Gadhafi's regime charged with killing protesters during the 2011 revolt that toppled him.

The officials include Gadhafi's once high-profile son Seif al-Islam -- who was unable to attend because he is being held by rebels in western Libya -- as well as former intelligence chief Abdallah al-Senussi.

Gunmen shot dead a naval officer in eastern Libya on Wednesday, a security official told Agence France Presse, the latest in a string of killings targeting members of the security forces.

"Unknown men fired at navy Captain Saleh al-Houdheiry, killing him instantly," in the city of Benghazi, security service spokesman Abdullah al-Zayedi told AFP.

Torture is widespread in Libyan detention centers run by brigades which emerged during the 2011 revolution, a U.N. report said Tuesday, urging Tripoli to bring all facilities under full state control.

"The report indicates that torture is widespread and most frequent immediately after arrest and during the first days of interrogation to extract confessions and other information," Ravina Shamdasani, a spokeswoman for the Office of the High Commissioner for Human Rights, told reporters.