BENGHAZI, Libya — Rebels battled Moammar Gadhafi’s forces Monday on a deadlocked front line in eastern Libya, and welcomed the first supply ship in five days to reach the besieged western port city of Misrata.

The heavy fighting was reported south of Ajdabiya, a rebel-held town about 90 miles south of Benghazi, the rebel headquarters in the east.

Hundreds of rebels gathered at a checkpoint outside Ajdabiya on Monday afternoon, when an AP photographer counted about 100 pickup trucks coming back from the front, each carrying four or five fighters and some with mounted submachine guns.

The rebels, firing their weapons into the air as they shouted and danced, said they had been told that NATO was going to launch airstrikes on Gadhafi’s forces and they had been ordered to withdraw temporarily from the front.

No casualty figures were available. Two ambulances came to the local hospital, and doctors said they carried the bodies of four rebels.

The cobbled-together rebel army – comprised of some deserters from Gadhafi’s forces and many civilians – has been bogged down for weeks in the area around Ajdabiya, unable to move on to the oil town of Brega. The rebels say their weapons cannot reach more than about 12 miles, while Gadhafi’s forces can fire rockets and shells up to twice that distance. Brega has an oil terminal and Libya’s second-largest hydrocarbon complex.

Rebel pleas for heavier arms from abroad have not been answered, although NATO is carrying out airstrikes on regime forces as many countries intensify their call for Gadhafi – Libya’s autocratic ruler for 42 years – to relinquish power.

The rebels control most of eastern Libya, and Gadhafi most of the west, including the capital, Tripoli. Exceptions in the west include pockets of embattled rebel-held towns along the border with Tunisia, and Misrata on the coast.

On Monday, Gadhafi’s forces shelled a northern neighborhood in Misrata where many families from the besieged city center have fled, said Abdel Salam, who identified himself as a resident turned fighter.

He said NATO airstrikes hit targets on the city’s southern edges, one of the areas where government forces have been concentrated after rebels pushed them back.

The fighting was threatening the port area, the city’s only lifeline, preventing some aid ships from docking, Abdel Salam said.

“We are in dire need for humanitarian and medical supplies. We also need arms and ammunition for self-defense,” he said. “We have no way to get this as long as the port is not secure.”