As warplanes took off from Italian bases and anti-aircraft guns roared in the Libyan capital, Gaddafi's army announced a new ceasefire Sunday, saying it was heeding an African Union call for an immediate cessation of hostilities.
But the United States accused Tripoli of lying about the ceasefire or breaching it immediately.
And United Nations Secretary General Ban Ki-moon said in a swift reaction:
"I sincerely hope and urge the Libyan authorities to keep their word.
"They have been continuing to attack the civilian population. This (offer) has to be verified and tested," he said.
An administrative building in Gaddafi's residential complex in Tripoli was flattened, an AFP journalist saw. The compound is surrounded by anti-aircraft guns.
The building is about about 50 meters (165 feet) from the tent where Gaddafi generally meets guests. It was hit by a missile, Libyan spokesman Moussa Ibrahim told journalists, who were taken to the site by bus.
"This was a barbaric bombing which could have hit hundreds of civilians gathered at the residence of Moamer Gadafi about 400 meters away from the building which was hit," Ibrahim said.
He denounced the "contradictions in Western discourses", saying: "Western countries say they want to protect civilians while they bomb the residence knowing there are civilians inside."
But the US denied targeting the residence or Gaddafi himself.
"I can guarantee he's not on the targeting list. We're not targeting his residence," vice admiral Bill Gortney told reporters.
However, the Libyan leader's "command and control capability," a coalition official told AFP Sunday, speaking on condition of anonymity.
"The coalition is actively enforcing UNSCR (UN Security Council Resolution) 1973, and that in keeping with that mission, we continue to strike those targets which pose a direct threat to the Libyan people and to our ability to implement the no-fly zone," the official said.
Gaddafi's regime had declared a ceasefire on Friday after UN Security Council resolution 1973 authorized any necessary measures, including a no-fly zone, to stop his forces harming civilians in the fight against the rebels.
But his troops continued attacking the rebel stronghold of Benghazi, sparking action by US, British and French forces from Saturday in line with the resolution.
In the West's biggest intervention in the Arab world since the 2003 US-led invasion of Iraq, US warships and a British submarine fired more than 120 Tomahawk cruise missiles into Libya late on Saturday, US military officials said.
The first round of strikes by aircraft and cruise missiles prompted a defiant Gaddafi to warn of a long war in the Mediterranean "battlefield".
Tripoli reported dozens of deaths, but Pentagon spokesman Gortney said:
"There is no indication of any civilian casualties."
US Defense Secretary Robert Gates said Sunday the United States would not play a "preeminent role" in military action against Libya, with other countries soon taking the lead.
British forces on Sunday took part in a "co-ordinated strike against Libyan air defense systems" for a second straight day, the defense ministry said.
"For a second time, the UK has launched guided Tomahawk Land Attack Missiles (TLAM) from a Trafalgar Class submarine in the Mediterranean as part of a coordinated coalition plan to enforce the (UN) resolution," a statement said.
London said the first day of air and sea strikes had been "very successful".
Meanwhile, the French aircraft carrier Charles de Gaulle sailed from Toulon on the 48-hour voyage to Libyan waters.
The US military said the first stage of coalition raids had been "successful", with Gaddafi's offensive on Benghazi stopped in its tracks.
Gortney told reporters the strikes had succeeded in "significantly degrading" Libyan air defenses, and a no-fly zone was now effectively in place over the country.
Earlier, dissenting voices in the wake of the first raids in Operation Odyssey Dawn became apparent, including from the Arab League which had backed the no-fly zone.
"What has happened in Libya differs from the goal of imposing a no-fly zone and what we want is the protection of civilians and not bombing other civilians," League Secretary General Amr Mussa told reporters.
"From the start we requested only that a no-fly zone be set up to protect Libyan civilians and avert any other developments or additional measures."
Mussa said preparations were now under way for an emergency meeting of the 22-member Arab League.
Russia, which abstained in Thursday's Security Council vote instead of using its veto, called for an end to "indiscriminate use of force" by the coalition, citing the casualties reported by Tripoli of 48 dead and 150 wounded.
China, another abstainer, expressed regret at the air strikes, saying it opposed using force in international relations.
Russian foreign ministry spokesman Alexander Lukashevich said the raids had included attacks on non-military targets, and had damaged roads, bridges and a cardiology centre.
Gortney said the cruise missiles "struck more than 20 integrated air defense systems and other air defense facilities ashore".
They were followed by strikes by manned aircraft including B-2 Stealth bombers which dropped 40 bombs on a Libyan military airfield, US officials said.
As Tripoli awaited new attacks, AFP journalists saw residents who had fled Benghazi returning to the rebel capital in eastern Libya.
Medics in Benghazi said that 85 civilians and rebels were killed in fighting with Gaddafi's forces on Friday and Saturday, while AFP correspondents counted nine bodies of Gaddafi loyalists in a hospital.
AFP correspondents and rebels said dozens of government military vehicles, including tanks, were destroyed on Sunday in air strikes west of the city.
According to the rebels, French warplanes -- which began the coalition operation with a strike at 1645 GMT on Saturday -- strafed government forces for two hours as day broke on Sunday.
The French spokesman said Paris had deployed 15 aircraft with air-to-air and air-to-ground capabilities.
A furious Gaddafi said on Sunday that all Libyans were armed and ready to fight until victory against what he branded "barbaric aggression".
"We promise you a long, drawn-out war with no limits," he said, speaking on state television for a second straight day without appearing on camera.
The leaders of Britain, France and the United States will "fall like Hitler... Mussolini," warned the strongman of oil-rich Libya.
"America, France, or Britain, the Christians that are in a pact against us today, they will not enjoy our oil," he said. "We do not have to retreat from the battlefield because we are defending our land and our dignity."
US President Barack Obama called Odyssey Dawn a "limited military action," unlike the regime change aims of the war against Iraqi president Saddam Hussein.
