* U.S. Navy SEALs storm vessel in international waters
* Raid likely to halt Libyan rebel attempts to ship oil (Adds details, background)
By Feras Bosalum and Ulf Laessing
U.S. special forces have seized a tanker that fled with a cargo of oil from a Libyan port, the U.S. Department of Defense said on Monday, halting an attempt by rebels to sell petroleum on the global market.
Libyan rebels demanding a greater share of oil wealth managed to load crude onto the ship, which escaped Libya's navy, embarrassing the government and prompting parliament to sack the prime minister.
U.S. Navy SEALs boarded the Morning Glory tanker in international waters off Cyprus on Sunday night and took control of the vessel, which the Pentagon said was held by three armed Libyans.
The tanker's seizure by U.S. forces is likely to prevent any more attempted oil sales by the rebels, who in August seized three export terminals accounting previously for 700,000 barrels a day of exports.
No one was hurt in the tanker raid, which was approved by U.S. President Barack Obama and requested by the Libyan and Cypriot governments, Pentagon Press Secretary John Kirby said.
"The Morning Glory is carrying a cargo of oil owned by the Libyan government National Oil Company. The ship and its cargo were illicitly obtained" from the Libyan port of Es Sider, his statement said.
The standoff over control of OPEC member Libya's oil is one facet of wider turmoil that has engulfed the vast North African country since the civil war that led to the fall of Muammar Gaddafi nearly three years ago.
It was the second time in six months that U.S. forces have become involved in Libya. A commando team snatched a suspected al Qaida suspect off the street as he returned home from prayers in the capital Tripoli in September.
The Cypriot ministry of foreign affairs said the vessel was now heading west in the Mediterranean with a U.S. military escort. It was parked 18 miles (29 km) southwest of Cyprus when the operation occurred around midnight Cyprus time.
The Pentagon statement said the vessel would be returned to a Libyan port.
There was no immediate reaction from the federalist rebels, based in eastern Libya, who said they would issue a statement later on Monday. They have been demanding more autonomy for their region.
Abb-Rabbo al-Barassi, self-declared prime minister of the rebel movement, said on Saturday his group was ready to negotiate an end to the port blockade, but the government needed to abandon plans to mount a military offensive.
Libya's parliament head, who has quasi-presidential powers, had given the rebels two weeks to withdraw from the seized ports or face a military operation.
But analysts said it was uncertain whether government troops would be able effectively to confront the heavily armed rebels, made up of soldiers who defected from an oil protection force.
The tanker's escape highlighted the weakness of government forces, which had claimed several times that the 37,000-tonne ship was under their control only for the vessel to slip into international waters after a firefight.
The government and nascent army have struggled to control brigades of former anti-Gaddafi fighters who have refused to disarm and have used their military muscle to make political demands on the state, often by targeting the vital oil sector.
FULL CONFRONTATION UNLIKELY
Libya has been trying to rebuild its army since Gaddafi's ousting, but analysts say it is not yet a match for battle-hardened militias that fought in the eight-month uprising that toppled the dictator.
While the navy did open fire on a Maltese-flagged tanker trying to approach Es Sider in January, analysts say a full military confrontation with the port rebels would be unlikely.
Any bloodshed would complicate efforts to negotiate a settlement with rebel leader Ibrahim Jathran, a former anti-Gaddafi commander who was in charge of protecting oilfields and ports until he turned against the government in the summer.
His campaign to seek more rights for Libya's underdeveloped east has won him some sympathy, but many people dismiss him as a tribal warlord with no political vision.
Any military conflict might boost his popularity and plans to establish a federalist state sharing power and oil wealth like under King Idris, who was toppled by Gaddafi in a 1969 plot.
The government fears federalism might open the door for secession and similar protests by other regions though the rebels say they do not want to break up Libya.
Libya's government faces a budget crisis as oil production has fallen to little over 200,000 barrels per day (bpd), from 1.4 million bpd in summer when a wave of protests at oilfields and ports started. Oil is the main source of revenues for the budget and to fund basic food imports.