Moammar Gadhafi's forces swept rebels from one of their final strongholds with hours of searing waves of strikes from warships, tanks and warplanes on Sunday but the insurgents claimed that they moved back in after nightfall.
One rebel said that after their initial defeat, opposition forces destroyed armored vehicles and captured dozens of fighters from Gadhafi's elite Khamis Brigade in the oil town of Brega, driving others back into the town's airport.
Another opposition fighter told The Associated Press by telephone that celebrations had broken out in the nearby city of Ajdabiya, and celebratory gunfire, honking and shouting could be heard in the background.
"We are on our way to Brega to celebrate with our brothers there," he said.
Earlier Sunday, the rebels spoke of their fears in the face of the advance of Gadhafi's forces, which have reversed much of the early gains made by opposition forces.
"The Libyan people need help. We're in danger. The east is in danger," Abdel Hadi Omar, a civilian rebel volunteer, speaking in the nearby town of Ajdabiya, said.
"The Libyan people can't cope with Gadhafi's weapons. We have people but we don't have means," he told Reuters.
The opposition has seen a series of reversals in its battle for control of Libya's main coastal highway, which runs from Gadhafi's western stronghold in the capital, Tripoli, to rebel-held territory in the east. Gadhafi's forces seem emboldened by their string of victories but their supply lines are increasingly stretched and they depend on artillery, airstrikes and naval attacks that are more difficult to launch at night.
The rebels have been pleading for Western powers to protect them with a no-fly zone, and on Monday their leaders meet in Paris with U.S. Secretary of State Hilary Rodham Clinton, who plans to assess their capabilities and intentions.
The Arab League asked the U.N. Security Council on Saturday to impose a no-fly zone. But the U.S. and many allies have expressed deep reservations about a tactic that would require them to destroy Gadhafi's air defenses and possibly shoot down his planes, and they appeared no closer Sunday to imposing a no-fly zone.
The poorly equipped and loosely organized fighters said throughout the day that they were fleeing Brega under heavy attack, losing a vital source of fuel for their vehicles and leaving Gadhafi's military less than 150 miles from the main opposition city of Benghazi.
A spokesman for Gadhafi's military declared that it had seized control of the town and was "dealing with the situation."
Ajdabiya is the only other major population center between Gadhafi's forces and the rebel headquarters. If his successes continue, the Libyan strongman will soon face the choice of consolidating his control of the Mediterranean coast or moving swiftly toward Benghazi and the prospect of a devastating battle.
"Benghazi doesn't deserve a full-scale military action," army spokesman Milad Hussein told reporters in the capital, Tripoli. "They are a group of rats and vermin and as soon as we go in, they will raise their hands and surrender."
Gadhafi's navy, army and air force began pounding Brega with artillery, rockets and bombs Sunday morning and didn't let up all day, forcing doctors and wounded people from the town's hospital with a missile strike, several rebels told The Associated Press after fleeing.
"There wasn't any time to breathe, to do anything," one fighter with responsibility for logistics said by telephone as he fled Brega for Ajdabiya, about 50 miles (80 kilometers) by road to the east. Explosions went off in the background.
Speaking on condition of anonymity for fear of retaliation, he said the opposition was bracing for conflict in Ajdabiya by evacuating doctors and the wounded from there, too.
He said some rebels had gathered in a seaside village a few miles east of Brega, hoping to halt Gadhafi's forces. He said more fighters from rebel strongholds in the east were heading to Ajdabiya to prepare for a battle there.
The rebels were trying to secure the southern and eastern roads to Ajdabiya and storing provisions and weapons there after the loss of free access to gasoline in Brega.
"I think they are bombing heavily because they want to win time before a no-fly zone is imposed," he shouted over the phone.
An opposition leader in Ajdabiya said the rebels planned to retake Brega and were attacking Gadhafi's forces with guns and roadside bombs as they moved in reinforcements from government-held cities in the west.
The rebels are fighting to oust Gadhafi from power after more than 41 years, inspired by protesters who toppled authoritarian rulers in neighboring Tunisia and Egypt. A week ago they held the entire eastern half of the country and were charging toward the capital, Tripoli. Then Gadhafi's troops began reversing those early gains with superior weaponrym and firepower from the air.
With much of the fighting in the east taking place along a coastal highway bounded by strips of desert, there are few places for the rebels to take cover, forcing them to withdraw under fire before attempting to surge back.
Also Sunday, Gadhafi's forces appeared to edge closer to Misrata, battling rebel fighters on the outskirts of Libya's third-largest city, 125 miles (200 kilometers) southeast of Tripoli, residents reported.
One resident, who did not want his name used because he fears for his safety, said streets inside the city were empty as people took cover in their homes and the noise of tanks, anti-aircraft fire and machine guns grew ever-nearer.
He said several tank shells had struck inside the city, hitting a mosque and an apartment building.