Details added (first version was published at 00:59)
US President Barack Obama said a limited US military action against Libya began on Saturday, as the Pentagon confirmed that more than 100 Tomahawk cruise missiles had been fired at Libyan air defences, dpa reported.
"I've authorized the Armed Forces of the United States to begin a limited military action in Libya," Obama said during a visit to Brazil. "That action has now begun."
Admiral William Gortney told reporters in Washington that US ships and one British submarine fired 110-112 cruise missiles at air defence targets including in cities of Tripoli and Misrata.
The defences are being targeted to help the international community enforce a no-fly zone over Libya and prevent Libyan leader Moamer Gaddafi from engaging in a brutal crackdown on civilians and anti-government forces in the country.
"The use of force is not our first choice," Obama said. "But we cannot stand idly by when a tyrant tells his people that there will be no mercy."
Gortney said it was difficult to evaluate the success of the initial attacks, given that darkness had fallen over Libya Saturday night. It would take 6-12 hours to discover whether Libya's air defences had been taken out.
"This is just the first phase of a multi-phase operation," Gortney said.