Western-led airstrikes pounded the Libyan capital of Tripoli and other targets early Thursday morning, prompting claims of civilian casualties that could weaken support for the U.N.-sanctioned mission aimed at protecting Libyans from the military might of their embattled longtime leader, Moammar Gadhafi.

Explosions followed by massive barrages of artillery fire shook Tripoli throughout the night. Gadhafi loyalists claimed a large number of civilian casualties and showed the Reuters news agency bodies that they said were those of civilian and military victims of airstrikes in the Tripoli suburb of Tajoura.

But a group of journalists traveling to a hospital in Tajoura to independently verify claims of civilian casualties was stopped and detained for 90 minutes So far, Libyan authorities have been unable to substantiate a single case of a civilian injured or killed or damage to civilian infrastructure caused by the bombings.

U.S. Secretary of Defense Robert M. Gates told the Arabiya news channel that the Western-led alliance, empowered by the U.N. to establish a no-fly zone, has succeeded in destroying most of Libya’s air defenses. French fighters said they shot down a Libyan warplane near the besieged rebel-controlled city of Misrata, the most significant rebel-controlled stronghold in western Libya.

Spokesmen for the Libyan opposition leadership in Benghazi, east of Tripoli, said allied air attacks also targeted government tanks and rocket batteries overnight in or near Ajdabiya, 95 miles south of the rebel capital. They said up to three tanks had been destroyed, but that could not be confirmed because reporters have been unable to reach the city.

Rear Adm. Gerard Hueber, a U.S. naval officer involved in directing the air campaign, told reporters via audio link from a ship in the Mediterranean Sea that government forces in Ajdabiya were among the targets hit by airstrikes, but provided no details.

State television broadcast what it described as a mass funeral for victims of bombing raids in Tajoura led by U.S., French and British air and naval forces. But they would not allow journalists to independently verify the claim.

Rebel fighters and forces loyal to Gadhafi have battled over Ajdabiya for the past week, with government forces pounding residential neighborhoods with tank and rocket fire. Rebel fighters say Gadhafi’s men are running low on fuel, ammunition and food because allied aircraft have cut their supply lines to the Gadhafi stronghold of Surt, 240 miles to the west.

Rebel fighters remained stuck roughly seven miles north of the city Thursday. They were spread out along the coastal highway and among sand dunes in the desert, vulnerable to rocket attacks. The rebels claim to control much of central Ajdabiya, but repeated forays have not dislodged Gadhafi fighters dug in at two entrances to the important crossroads city of 120,000.

Most residents have fled, but those who remain are huddled in their homes without electricity, water or cooking gas. Those services have been cut off by government forces, according to the rebels.

Mustafa Gheriani, an opposition spokesman in Benghazi, said rebel forces control 80 percent of Ajdabiya. But he conceded that they lack the firepower to drive remaining government fighters from the city without airstrikes to destroy heavy weapons that give Gadhafi’s troops a decided advantage.

Residents of Misrata, Libya’s third largest city, reported relative calm after days of shelling by Gadhafi’s forces inside and outside the city. “”People are imprisoned in their houses because of the snipers,”” said a pharmacist in Misrata reached via an Internet voice connection.