By Michael Georgy
RAS LANUF, Libya (Reuters) - Muammar Gaddafi's troops forced outgunned Libyan rebels to retreat eastwards on Sunday and laid siege to pockets of resistance, unimpeded by diplomatic efforts to impose a no-fly zone.
The United States said a call by the Arab League for a U.N. no-fly zone over Libya was an "important step," but while Washington said it was preparing for "all contingencies," it has remained cautious over endorsing direct military intervention.
Arab League Secretary General Amr Moussa said the League had "officially asked the U.N. Security Council to impose a no-fly zone against any military action against the Libyan people."
That would appear to satisfy one of the factors that NATO has said is needed for it to take on the task of policing Libyan air space, that of strong Arab support. But the other, a U.N. mandate, is still not in sight.
The United States does not want to appear to be leading the drive to oust Gaddafi and made no proposal for an emergency meeting of the U.N. Security Council. Diplomats in New York said a Security Council meeting at the weekend was unlikely.
Even if the Security Council does come together to discuss a Libyan no-fly zone, it is far from clear whether it would pass a resolution as veto holders Russia and China have both publicly opposed the idea.
BREGA UNDER ATTACK
The lengthy diplomatic negotiations run the danger of being overtaken by events on the ground as Gaddafi's troops pressed home their advantage in armor and air power and pushed the rag-tag insurgent forces back on the oil town of Brega, some 220 km (137 miles) south of the rebel stronghold of Benghazi.
Libyan state television said "Brega has been cleansed of armed gangs," but the report could not be immediately confirmed.
Some residents had fled Brega in fear, and rebels again appealed for foreign help to stop Gaddafi's warplanes.
Losing Brega and its refinery would limit rebel access to fuel after the insurgents were pushed out of Ras Lanuf on Sunday, another major oil terminal some 100 km to the west.
"The Libyan people need help. We're in danger. The east is in danger," said Abdel Hadi Omar, a civilian rebel volunteer. "The Libyan people can't cope with Gaddafi's weapons. We have people but we don't have means."
Rebels do not want the support of foreign ground troops.
"We believe that, with (a no-fly zone), we will be able to prevail," said Hafiz Ghoga, a spokesman for the rebel National Libyan Council.
Fresh from crushing the revolt in Zawiyah, west of the capital Tripoli, government tanks and troops turned to Misrata, Libya's third biggest city and the only pocket of rebel resistance outside the east.
But a mutiny among government troops slowed the advance of a crack Libyan brigade commanded by Gaddafi's son Khamis advancing on Misrata, with 32 soldiers joining the rebels holding the city, a rebel there said. He said one defector was a general.
Rebel spokesman Gamal said the brigade, stalled about 10-15 km south of the city as fighting broke out in the ranks, with dozens of troops balking at the idea of killing civilians in the impending attack.
The events could not be confirmed independently. Journalists have been prevented from reaching the city by the authorities.
Mussa Ibrahim, a government spokesman in Tripoli, could neither confirm nor deny a military operation was under way in Misrata.
"There is a hard core of al Qaeda fighters there," he said. "It looks like a Zawiyah scenario. Some people will give up, some will disappear ... Tribal leaders are talking to them. Those who stay behind, we will deal with them accordingly."
It took a week of repeated assaults by government troops, backed by tanks and air power, to crush the uprising in Zawiyah, a much smaller town 50 km (30 miles) west of Tripoli.
The death toll in Zawiyah is unknown but much of the town was destroyed, with buildings around the main square showing gaping holes blown by tank rounds and rockets. Gaddafi's forces bulldozed a cemetery where rebel fighters had been buried.
After fighting ceased in Zawiyah on Friday, one soldier there was asked about the fate of rebels. He made a throat-cutting gesture and laughed.
As in Zawiyah, the rebels in Misrata were heavily outgunned.
"We are bracing for a massacre," said Mohammad Ahmed, a rebel fighter. "We know it will happen and Misrata will be like Zawiyah, but we believe in God. We do not have the capabilities to fight Gaddafi and his forces. They have tanks and heavy weapons and we have our belief and trust in God."
(Additional reporting by Maria Golovnina in Zawiyah, Mohammed Abbas in Brega, Tom Pfeiffer in Benghazi, Mariam Karouny in Ras Jdir, Tunisia, Alister Bull in Washington; Writing by Jon Hemming; Editing by Jon Boyle)