Overnight, at least five NATO air strikes targeted Tripoli, sending plumes of smoke over the Libyan capital and several sharp explosions could be heard. One strike targeted a government building but it was not immediately clear what the other four strikes hit.
Burning flares cascaded down from the sky. Some residents responded by raking the sky with gunfire and beeping their horns.
On the front line, heavy fighting was reported south of Ajdabiya, a rebel-held town about 90 miles (150 kilometers) 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 overall 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 (20 kilometers) 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 met any response, 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 leave power.
The rebels now 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 where many families from the besieged city center have fled to, 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."
A ship carrying medical supplies and baby food was able to dock in Misrata on Monday, according to the International Committee of the Red Cross.
It was the first ship to arrive since Wednesday, when Gadhafi's forces fired a barrage of rockets into the port as the International Organization of Migration was evacuating nearly 1,000 people, mainly African migrant workers.
On Saturday, a rocket attack set the city's main fuel depot ablaze, destroying the main supply for vehicles, ships and generators powering hospitals and other key sites in a city darkened by electricity cuts.
The ICRC said it would use the chartered ship as a floating platform as its team works to reduce the danger of unexploded weapons on the streets of Misrata, visit prisoners detained by the rebels and help reunite families that lost contact when the city center was bombed.
The ship brought in 8,000 jars of baby food as well as urgently needed surgical instruments and medical dressings.
The ship docked safely though Gadhafi's forces were seen dropping mines into the port on Saturday from a white helicopter painted with a red cross, according to rebel spokesman Abdel-Hafidh Ghoga and Misrata residents.
The ICRC said it was concerned by those allegations of "a serious misuse of the emblem" designated by the Geneva Conventions to be used solely by people providing medical or other humanitarian aid.
A civilian spokesman for the rebels in Misrata, lawyer Abdulbaset Abumzirig, said Sunday that 30 to 40 people are injured daily and 10 to 15 are being killed by the bombardment. The city has been under siege for two months, and local doctors say the total death toll is more than 1,000.
In Tripoli overnight, NATO aircraft targeted at least five sites. Reporters taken by government officials to one building saw a hole punched into what appeared to be its basement and thick blocks of concrete cracked into dusty rubble.
The building was partially used by parliament members and hosted a library to research Gadhafi's Green Book - a tome penned by the Libyan leader that citizens are expected to study, said government workers Hussein Bengarsa and Mousa Saleh.
But there were no papers or books scattered around the area, nor office supplies normally associated with such use.
The handsome pastel-colored building was built by Italians when they ruled Libya in the 1920s. It once served as Italy's naval headquarters and was considered an iconic Tripoli site.
It was not immediately clear what the other strikes targeted. Reporters may not leave their Tripoli hotel without government minders.
Also in the capital, a Muslim member of Britain's House of Lords warned of "genocide" if Libya's chaos continues.
Lord Nazir Ahmed said he feared that if Gadhafi's forces seized control of areas currently ruled by rebels - or vice versa - there could be widespread revenge killings.
"God forbid if any one side wins - for instance, if the government takes control of Benghazi, what would happen to all those rebels?" he said. "And if they (the rebels) win, what will happen to the government supporters?"
Ahmed spoke before a meeting with Libyan tribal chiefs as a part of a two-day private fact finding mission. He said he would seek to visit rebel-ruled eastern Libya soon.
Meanwhile, the U.N. humanitarian chief, Valerie Amos, asked all sides in the fighting for a pause in hostilities to allow food, water, medical supplies and other aid to be delivered to needy populations.
She told the Security Council the pause would also allow humanitarian workers to evacuate people from other countries who still remain in Libya and would give civilians a respite.
Associated Press writer Diaa Hadid in Tripoli and AP photographer Rodrigo Abd in Ajdabiya contributed to this report.