Loud explosions and barrages of anti-aircraft fire have been heard near the Tripoli compound of Libyan leader Muammar Gaddafi tonight.
The explosions happened at around 7pm Irish time near the Bab el-Aziziya barracks in the south of Tripoli.
Similar explosions rocked the capital last night, with coalition officials saying that an administrative building in Gaddafi's fortified complex had been destroyed by a cruise missile.
Britain, France and the US began launching strikes with aircraft and cruise missiles on targets in Libya on Saturday evening.
The air strikes are in line with a UN Security Council resolution authorising any measures to stop Gaddafi harming civilians in a campaign by his forces to subdue an uprising.
A Libyan government spokesman has said that 'many people' have been killed in attacks on ports and the city of Sirte today.
Meanwhile, US President Barack Obama has said NATO will be involved in helping to coordinate the next phase of action in Libya
Mr Obama said he expected some kind of transfer of command within days and not weeks.
'Obviously the situation is evolving on the ground,' Mr Obama said at a press conference with Chilean President Sebastian Pinera after talks in Santiago.
'As I said, our initial focus is taking out Libyan air defences so that a no-fly zone can operate effectively and aircraft and pilots of the coalition are not threatened when they're maintaining the no-fly zone.
'The second aspect of this is making sure that the humanitarian aspects of the mission can be met. But let me emphasise that we anticipate this transition to take place in a matter of days and not a matter of weeks.'
He added that he anticipated that 'NATO will be involved in a coordinating function because of the extraordinary capacity of that alliance'.
Mr Obama also said that it is US policy is that Gaddafi leave power, but stressed the US would stick to the UN mandate in its military action in Libya.
He said: 'Our military action is in support of an international mandate from the Security Council that specifically focuses on the humanitarian threat posed by Colonel Gaddafi to his people.'
'No decent future' under Gaddafi - Cameron
British Prime Minister David Cameron earlier told MPs in the House of Commons that Libya has 'no decent future' under Gaddafi.
British MPs have passed a House of Commons motion supporting the government's decision to commit British armed forces to Libya by 557 votes to 13.
Elsewhere, Gaddafi's forces stormed the western city of Misrata, killing at least 40 people.
A rebel spokesman in Misrata said Gaddafi loyalists had opened fire with tanks, while snipers on roofs picked off people in the streets.
A medic in the city, speaking by telephone, confirmed a death toll of 40 and said at least 300 people had been injured.
Arab League 'respects' UN resolution
Arab League Secretary General Amr Moussa has said he respected a UN resolution authorising military action in Libya.
Comments over the weekend suggested he was concerned by actions taken by Western powers.
'We respect the UN resolution and there is no conflict with it, especially as it indicated there would be no invasion but that it would protect civilians from what they are subject to in Benghazi,' he said.
The UN-mandated intervention to protect civilians caught up in a one-month-old revolt against Muammar Gaddafi had drawn comments from Mr Moussa yesterday, suggesting he questioned the need for a heavy bombardment that he said had killed many civilians.
However, speaking today at Arab League headquarters in Cairo, Mr Moussa said: 'It is for protecting civilians and that is what we care about.
'We will continue to work on the protection of civilians. We urge everybody to take this into consideration in any military action.'
