Fresh attacks by Western forces on Libya flattened a building in leader Moamer Kadhafi's compound but Britain said on Monday it had aborted one strike because of the presence of civilians.
The second night of Operation Odyssey Dawn, to enforce a UN Security Council resolution aimed at stopping Kadhafi's forces harming civilians as they battle an uprising, again saw strikes by aircraft and cruise missiles.
Meanwhile Kadhafi's forces pulled back from the rebel capital of Benghazi after fierce attacks by coalition aircraft.
As warplanes took off from Italian bases and anti-aircraft guns roared in the Libyan capital, Kadhafi's army announced a new ceasefire late Sunday, but the United States promptly accused Tripoli of lying or of breaching the truce 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."
The administrative building destroyed in Kadhafi's residential complex in Tripoli was about 50 metres (165 feet) from the tent where he generally meets guests.
It was hit by a missile, Libyan spokesman Mussa Ibrahim told journalists, including an AFP reporter, 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 Kadhafi about 400 metres away from the building which was hit," Ibrahim said.
He slammed 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 United States denied targeting Kadhafi or his home.
"I can guarantee he's not on the targeting list. We're not targeting his residence," Pentagon spokesman Vice Admiral Bill Gortney told reporters.
However, the strike destroyed the Libyan leader's "command and control capability," a coalition official told AFP.
"The coalition is actively enforcing UNSCR 1973, and 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" authorised by the resolution, the official said.
Kadhafi's regime had declared a ceasefire on Friday after Resolution 1973 was passed, but his troops continued attacking the rebel stronghold of Benghazi, sparking action by US, British and French forces from Saturday.
However US officials said American forces would be taking more of a back seat after the initial effort to destroy Libya's defences, with other countries, including Arab states, enforcing the no-fly zone.
"We will have a military role in the coalition. But we will not have the pre-eminent role," Gates said.
In deciding to back intervention in Libya, Obama stressed the "importance of a meaningful coalition" with partners "making serious military contributions," Gates said.
"It is pretty clear that we agreed to use our unique capabilities and with the breadth of those capabilities at the front end of this process, then we expected in a matter of days to be able to turn over the primary responsibility to others," he said.
Washington is keen not to be seen as leading the West's biggest intervention in the Arab world since the 2003 US-led invasion of Iraq, though Arab protests about the action against Kadhafi, who is widely detested, have been muted.
Gortney said the first strikes, involving US B2 stealth bombers flown from the United States and more than 100 cruise missiles launched from ships offshore, had succeeded in "significantly degrading" Libyan air defences, and a no-fly zone was now effectively in place over the country.
Britain's defence ministry said British forces had joined in the second round of attacks, launching cruise missiles from a Trafalgar Class submarine in the Mediterranean.
But military spokesman Major General John Lorimer said Monday that British Tornado jets pulled back from attacking Libyan air defence systems overnight because of a fear of hitting civilians.
"As the RAF GR4 Tornados approached the target, further information came to light that identified a number of civilians within the intended target area. As a result the decision was taken not to launch weapons," he said in a statement.
"This decision underlines the UK?s commitment to the protection of civilians."
Tripoli reported 48 dead and 150 wounded in the first strikes but Pentagon spokesman Gortney said: "There is no indication of any civilian casualties."
Reporters taken to a Tripoli cemetery Sunday by Libyan officials saw many open graves prepared for bodies which failed to appear.
"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.
As well as the attacks on Libya's defences Sunday, French fighters strafed government forces which had been attacking rebel-held Benghazi in the east, hitting tanks and other vehicles.
As a result, Kadhafi's forces fell back 100 miles (160 kilometres) from Benghazi to Ajdabiya, leaving dozens of destroyed tanks all along the road, an AFP reporter on the spot said.
Hundreds of rebels followed up the retreat, massing three to four kilometres (one to two miles) outside Ajdabiya.
A furious Kadhafi said 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 but without appearing on camera.
"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."
The weekend blitz caused oil prices to soar again as Asian markets opened on Monday.
New York's main contract, light sweet crude for delivery in April, gained $1.85 to $102.92 per barrel while Brent North Sea crude for May was up $1.73 to $115.66 in the afternoon.
Analysts said traders feared more damage to oil installations in Libya and the spreading of unrest to other parts of the oil-rich Middle East.
Source: AFP Global Edition