U.S. officials say a series of coalition airstrikes over Libya has succeeded in enforcing a UN-sanctioned no-fly zone.

"We judge these strikes to have been very significant in degrading the regime's air defence capability," aimed at its long-range surface-to-air missiles, Vice-Admiral Bill Gortney said at a Pentagon briefing Sunday, two days into the air assault.

Gortney also said Libyan leader Moammar Gadhafi himself is not a target, but he could not guarantee the strongman's safety.

CNN reported Sunday night that a four-storey building in Gadhafi's Tripoli compound had been heavily damaged. Government officials invited a CNN crew to see the building, alleging it was hit by cruise missiles. The Libyan leader's wheareabouts are unknown.

Gortney said no coalition aircraft had been shot down and there was no evidence the air assault had harmed civilians in Libya. He said all pilots returned safely from their missions.

Earlier, Admiral Mike Mullen, chair of the U.S. Joint Chiefs of Staff, said the assault by coalition forces "went very well" and a no-fly zone over Libya was now in place.

Loud explosion

Anti-aircraft fire followed by a loud explosion was reported in the Libyan capital late Sunday despite a renewed promise of a ceasefire by the country's armed forces, following a weekend of airstrikes by U.S.-led coalition forces.

Colourful streams of tracer fire could be seen heading skyward over the capital, but there was no immediate sign of a resumption of the missile attacks and aerial bombings that U.S. and European forces launched on Saturday.

A similar ceasefire call on Friday — just hours after the UN Security Council gave the go-ahead to a no-fly zone — was largely ignored by forces loyal to leader Moammar Gadhafi.

Earlier Sunday, Gadhafi predicted a "long war" against Libyan rebels and the coalition of countries helping them.

Gadhafi appeared as defiant as ever after a night of explosions, which rocked Tripoli and other coastal areas and left the road to the rebel city of Benghazi strewn with charred government military vehicles.

Libyan state television said 48 people were killed and 150 others injured, but the numbers have not been confirmed.Vehicles belonging to forces loyal to Libyan leader Moammar Gadhafi explode after an air strike Sunday by coalition forces, along a road between Benghazi and Ajdabiyah. (Goran Tomasevic/Reuters)

At least 124 missiles were fired during the attacks launched late Saturday to enforce the no-fly zone mandated by the UN Security Council and to weaken Gadhafi's air defences.

Tanks halted

Rebels had been losing ground to Gadhafi's forces in recent days and begged the international community to intervene. Government tanks were on the outskirts of Benghazi on Saturday, but Mullen said the allied attacks stopped the approach.

Gadhafi told state TV that arms depots around the country were being opened up to citizens so they could defend themselves against what he called terrorism and a "crusading aggression."

The CBC's Nahlah Ayed, reporting from neighbouring Egypt, said Gadhafi tried to portray the conflict as a religious one, accusing Western "Christian" powers of waging war on Islam. Ayed said this interpretation was bound to fail, however, since Gadhafi has never been a strong defender of Islam.

Rebels said the international strikes also hit an air force complex outside Misrata. After dawn Sunday, Gadhafi forces started bombing Misrata, the only rebel-held city in western Libya, opposition forces said.

During the international operation, Tomahawk cruise missiles were fired from American and British ships and submarines at more than 20 coastal targets, the U.S. military said. French fighter jets fired the first shots.

The secretary general of the Arab League, Amr Moussa, appeared to have reservations about the bombardment — developments that he said went beyond the enforcement of a no-fly zone. Moussa called for an emergency meeting of all 22 members of the Arab League to discuss the Libya situation.

However, the Arab League later reaffirmed its support for the no-fly zone.

Canada's planes could be flying Monday

Warplanes from the United States, Canada and Denmark arrived at Italian air bases Saturday. Germany backed the operation but isn't offering its own forces.

Spain, Belgium and the first Arab country, Qatar, have also joined the coalition.

Six Canadian jet fighters are part of the allied force but did not take part in the first wave. The fighter jets are at Trapani, Italy and were expected to begin operations Monday.

Prime Minister Stephen Harper's office said Saturday it would be at least 48 hours before Canada could take part in any bombing.

Harper defended Canada's involvement in the coalition force, saying the Gadhafi regime will kill anyone suspected of being disloyal.

Gadhafi's regime acted quickly in the run-up to the strikes, sending warplanes, tanks and troops into Benghazi, the first city to fall to the rebellion that began Feb. 15. Then the government attacks appeared to go silent.

A Benghazi resident who works for the Red Cross told CBC News that a quiet had fallen over the city after the allied intervention, like the "calm before the storm," but people were feeling optimistic.

Rebels had been upset at how long it was taking to get the military action under way, said the woman, who did not want her name used after just losing her neighbours to Gadhafi gunmen.

With files from James Cudmore and The Associated Press