(Changes attribution in paragraph five to a U.S. defense official, not Kirby)
* U.S. Navy commandos storm vessel in international waters
* Raid likely to halt Libyan rebel attempts to ship oil
By Ulf Laessing and Feras Bosalum
TRIPOLI, March 17 (Reuters) - U.S. special forces have seized a tanker that fled with a cargo of oil from a Libyan port controlled by anti-government rebels, halting their attempt to sell crude on the global market.
Gunmen demanding regional autonomy and a share of oil wealth had managed to load the ship, which escaped Libya's navy and triggered a crisis that prompted parliament to sack the prime minister.
A U.S. SEAL commando team boarded the tanker Morning Glory from a Naval special warfare rigid inflatable boat as it sat in international waters off Cyprus on Sunday night.
The seizure was approved by U.S. President Barack Obama and requested by the Libyan and Cypriot governments, Pentagon Press Secretary John Kirby said.
No one was hurt in the under two hour operation, and no shots fired. Two AK47 rifles were found and the three Libyans holding the ship remained in U.S. control, a U.S. defense official said, speaking on condition of anonymity.
"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, Kirby's statement said.
The standoff over Libyan oil and the tanker debacle have deepened the chaos testing Tripoli since the civil war that toppled Muammar Gaddafi nearly three years ago.
With its army still nascent, a weak government has been unable to impose its will on former anti-Gaddafi fighters and militias who now use their military muscle to make demands on the state, often by targeting the vital oil sector.
At least in the short term, the tanker's seizure by U.S. forces is likely to prevent any more attempted oil sales by the rebels, who in August took control of three export terminals accounting previously for 700,000 barrels a day of exports.
"Oil is the economy's artery. The government will not allow anyone to fool around with the assets and resources of the Libyan people," the Libyan government said in a statement.
It was the second time in six months that U.S. forces have become involved in Libya. A commando team snatched a suspected al Qaeda suspect off the street as he returned home from prayers in the capital Tripoli in September.
The Cypriot foreign ministry said the vessel was now heading west in the Mediterranean with a U.S. military escort.
An American crew from the USS Stout, a guided missile destroyer, got the tanker underway toward Libya on Monday. The Stout voyage was expected to take up to four days, the officials said.
The Morning Glory had been North Korean-flagged, but the government in Pyongyang on Thursday said it had notified Libya and maritime authorities that it had severed all ties with the ship because of the vessel's contraband cargo.
So Se Pyong, North Korea's ambassador in Geneva, said on Monday he discussed the situation with his Libyan counterpart to explain, but not apologise for the situation.
He said North Korea did not buy oil from Libyan rebels, and since the Egyptian-based shipping firm had acting illegally he was not concerned about the U.S. Navy seizure.
"Whether it was captured by the Americans, or by someone else, if that ship was doing something wrong, then we don't care," So told Reuters.
There was no immediate reaction from the federalist rebels, based in eastern Libya.
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.
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.
LEAR JET TO CYPRUS
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.
Still, the intervention gives a boost to the fragile Libyan government in its fight to impose order. The transition to democracy has been upset by tribal, regional and political disputes.
Western powers, worried that it might fracture or slide deeper into chaos, have been training Libyan armed forces and cajoling conflicting parties in government to reach a settlement, with little progress.
A successful sale of Libyan oil outside government control, though, was always going to be complicated for the rebels.
A Cypriot police source said three men - described as two Israelis and a Senegalese - were detained for questioning on Saturday on suspicion of attempting to buy the tanker's cargo, but were freed after a court refused to issue an arrest warrant.
Two of the men carried diplomatic passports - one from Senegal and one from a central African country, the security source said.
The source said they flew a Lear Jet into Cyprus on Friday evening, chartered a vessel from a yachting marina in Larnaca and headed to the tanker.
"They spoke to somebody on board the vessel, then left. At Larnaca marina police called them in for questioning," the source said. The men left for Tel Aviv after being freed.
The Libyan navy opened fire on a Maltese-flagged tanker trying to approach Es Sider in January, but analysts say a full military confrontation with the port rebels would be unlikely.
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.
Tripoli faces a budget crisis as oil production has fallen to a little over 200,000 barrels per day (bpd), from 1.4 million bpd in summer when protests at oilfields and ports started. (Additional reporting by Chris Michaud, Michele Kambas, Phil Stewart and Tom Miles; Writing by Patrick Markey, editing by Dale Hudson, William Hardy and Kevin Liffey)