Nato has agreed to take control of enforcing a no-fly zone in Libya to thwart the forces of leader Muammar Gaddafi, as coalition air strikes targeted Tripoli for the sixth straight day.
Nato secretary general Anders Fogh Rasmussen said on Thursday that after lengthy negotiations the 28-member alliance reached a deal to enforce the no-fly zone.
"We are taking action as part of a broad international effort to protect civilians against the Gaddafi regime," he said.
Rasmussen said the Nato operation was limited to enforcing the no-fly zone, but a senior US official, speaking on condition of anonymity later in Washington, said that Nato reached a "political agreement" to also command all other operations aimed at protecting civilians — meaning strikes against Gaddafi's ground forces.
The news came as anti-aircraft fire raked the Tripoli skies late on Thursday, with at least three explosions shaking the capital and its Eastern suburb of Tajura,journalists reported.
"At least one blast was heard from the centre of the city, while others came from Tajura, home to military bases."
Libyan state television said that 'civilian and military sites in Tripoli and Tajura' had come under fire from 'long-range missiles'.
Fighting also raged in rebel-held Misrata, some 214 kilometres (132 miles) East of Tripoli. A doctor treating the wounded at a hospital said attacks by Gaddafi forces since March 18 "have killed 109 people and wounded 1,300 others, 81 of whom are in serious condition."
Relentless British, French and US air strikes since Saturday have been targeting Gaddafi's air defenses in a bid to protect civilians under the terms of a UN resolution.
The strikes also provide cover for a rag-tag band of rebels seeking to oust Gaddafi after more than four decades in power, but who are disorganized and out-gunned by pro-regime forces.
A Gaddafi fighter plane that dared to flout the no-fly zone was swiftly punished on Thursday when a French fighter destroyed the jet after it landed in the city of Misrata East of Tripoli, the French military said.
Washington, meanwhile, urged the Libyan military to ignore Gaddafi's orders.
"Our message is simple: stop fighting, stop killing your own people, stop obeying the orders of Colonel Gaddafi," Vice Admiral William Gortney said.
"It's fair to say the coalition is growing in both size and capability every day," he said, adding 'more than 350 aircraft are involved in some capacity. Only slightly more than half belong to the United States."
The Pentagon said 12 countries were now taking part in the coalition seeking to enforce the no-fly zone — including two Arab nations, Qatar and the United Arab Emirates. A senior US official said the UAE had contributed 12 aircraft.
Allied diplomats spent the day negotiating how to coordinate the campaign against Gaddafi, how far to enforce the UN resolutions, and how to incorporate assistance from non-Nato Arab countries.
"We have agreed, along with our Nato allies, to transition command and control for the no-fly zone over Libya to Nato," secretary of state Hillary Clinton said, speaking after meeting with President Barack Obama and the US national security team.
"All 28 allies have also now authorized military authorities to develop an operations plan for Nato to take on the broader civilian protection mission under resolution 1973."
Clinton said that 'significant progress' had been made in just five days, but that the 'danger is far from over, and Gaddafi's forces 'remain a serious threat to the safety of the people'.
Clinton also underscored 'crucial' Arab support for the operation, and praised Qatar and the United Arab Emirates for joining the coalition.
The state department later said that Clinton will attend a London conference on Tuesday on military action against Libya.
French President Nicolas Sarkozy meanwhile said coordination of the international campaign must 'remain eminently political' even if Nato takes military command.
"Operational, technical coordination will be at Nato level, but political coordination. Will be at the level of the coalition," he said at a European Union summit in Brussels.
That would enable non-Nato members, such as Arab partners, to take part in political decision-making, he said.
Anti-aircraft fire and explosions also rattled the coastal city of Sirte, Gaddafi's home town 600 kilometres (370 miles) east of Tripoli, a resident said.
Gaddafi forces attacked Zentan, East of Tripoli, as rebels fought to retake the oil city of Ajdabiya, which sits at a junction on roads leading from rebel strongholds Benghazi and Tobruk in eastern Libya.
Rebels were in striking distance of Ajdabiya, an AFP journalist said, with shelling and gunfire heard nine kilometres (five miles) from the city.
"They are shooting at us with tanks, artillery and Grad missiles," said Mohammed, a rebel returning from the frontline. "We have nothing but light weapons."
The rebel army spokesman, Air Force general Ahmed Omar Bani, told reporters in Benghazi at his first news conference that some Gaddafi loyalists in Ajdabiya have asked to surrender.
"We are trying to negotiate with these people in Ajdabiya because we are almost sure that they have lost contact with the headquarters," Bani said.
There were also reports from the southern stronghold of Sebha — bastion of Gaddafi's Guededfa tribe and site of an important military base — of intense coalition air raids.
A government spokesman in Tripoli said almost 100 civilians had been killed since coalition air strikes began Saturday, a figure that could not be independently confirmed.
The US general in charge of the operation, General Carter Ham, said coalition forces imposing the no-fly zone 'cannot be sure' there have been no civilian deaths, but are trying to be 'very precise'.
Ham, head of US Africa command, also said Libya's air defences 'essentially no longer exist' after being destroyed in strikes, and that coalition forces were now targeting Libyan troops attacking civilians.
At the UN headquarters in New York, Secretary General Ban Ki-moon told the Security Council that Gaddafi's troops were ignoring the UN ceasefire order, and that human rights abuses continued in Libya.
"Libyan authorities have repeatedly claimed they have instituted a ceasefire," Ban said. "We see no evidence that that is the case. On the contrary, fierce battles have continued."
Separately, Russian President Dmitry Medvedev telephoned Obama to urge him to avoid civilian casualties in Libya and limit the campaign to the UN-set goals.
Russia abstained from last week's vote authorising the no-fly zone.
But French foreign minister Alain Juppe of France said coalition air strikes would 'continue for as long as necessary'.