The US Navy handed over to Libyan authorities Saturday an oil tanker it boarded after the vessel took to sea with crude illegally loaded at a rebel-held port, the American embassy said.
"Earlier today, US forces turned control of the M/T Morning Glory over to the government of Libya," a statement said.
"The handover took place in international waters off the coast of Libya, and the government of Libya and its security forces are now in control of the vessel."
The embassy said the transfer of the Egyptian-owned tanker had taken place "smoothly and as planned".
"We have been assured by the government of Libya that the captain, crew members and Libyan nationals who were aboard the stateless tanker will be treated humanely in accordance with internationally recognised standards of human rights," it said.
US Navy SEALS captured the Morning Glory off Cyprus in the eastern Mediterranean on Monday.
The ship last week slipped through a Libyan naval blockade off the eastern port of Al-Sidra -- controlled by rebels seeking autonomy from Tripoli -- after reportedly being loaded with some 234,000 barrels of crude.
On Saturday, pro-autonomy rebels and government forces clashed in the eastern city of Ajadabiya, leaving an unknown number of casualties, an AFP journalist and military sources said.
A senior military official said the clashes broke out around an army barracks in the east of the city. There were casualties on both sides, he said, without giving figures.
The rebels, whose forces have been blockading the eastern ports, were fighting to recapture the barracks from government forces, one of their commanders said.
The AFP journalist reported heavy gunfire in Ajadabiya and columns of smoke from the vicinity of the barracks.
- Autonomy for Cyrenaica -
The weak Tripoli government's failure to lift the blockades and stop the Morning Glory had plunged Libya into one of its biggest crises since Moamer Kadhafi was toppled by a NATO-backed uprising in 2011.
No one was hurt when US forces, at the request of both Libya and Cyprus, "boarded and took control" of the tanker operated by three armed Libyans, the Pentagon said.
Its escape after Libyan authorities had repeatedly vowed to take all measures to stop it underscored the weakness of the central government, which has struggled to rein in heavily armed former rebels.
Rebels pressing for autonomy for Libya's eastern Cyrenaica region -- epicentre of the revolt against Kadhafi -- have been blockading oil terminals in eastern Libya since July.
That has led to a decline in exports from 1.5 million barrels a day to just 250,000.
The Morning Glory incident marked a major escalation and triggered the ouster of liberal-backed prime minister Ali Zeidan.
The Morning Glory was originally a North Korean-flagged ship, but Pyongyang said it had "cancelled and deleted" its registry on the grounds it was carrying contraband material.
The United States has viewed the chaos in Libya with growing alarm since an attack on its consulate in the eastern city of Benghazi in September 2012 that killed US Ambassador Chris Stevens and three other Americans.