Libyan state television said there had been a fresh wave of strikes on Tripoli early on Sunday. European and American warplanes have fired at least 110 missiles on strategically important cities over the past hours.
French warplanes fired the first shots at Libyan military forces in the eastern city of Benghazi.
Hours later, American and British warships and submarines fired missiles at targets in the capital Tripoli and the western city of Misratah.
Heavy bursts of anti-aircraft fire, machine guns and explosions have been heard in Tripoli.
CBS News reported that three US B-2 stealth bombers had dropped 40 bombs on a “major Libyan airfield.”
Libyan state television announced that 48 people were killed and 150 were wounded in the strikes, including civilians.
The action follows a Thursday UN Security Council resolution which endorsed intervention in Libya.
Canada is also sending warplanes to the region, while Italy has offered the use of its military bases.
However, China, Russia and the African union have condemned military action.
Gaddafi has promised retaliation, saying he will open arms depots to people to fight the allied forces.
“We promise you a long, drawn-out war with no limits,” Gaddafi said on state TV on Sunday morning.
It is the biggest Western military intervention in the Arab world since the 2003 invasion of Iraq