The strikes followed a lull in NATO bombing of Tripoli, but in the evening loud blasts rocked the city with plumes of smoke filling the sky to the east and aircraft flying overhead.

Libyan state TV said the bombs had struck military and civilian targets in Firnag, one of the most populated areas in the capital, and Ain Zara. It said there were casualties.

Earlier in the day rebels tried to advance in the east, setting their sights on the oil town of Brega to extend their control over the region, epicenter of the four-month rebellion against Gaddafi's four-decade rule.

NATO defense chiefs met in Belgrade to discuss the mission, after Defense Secretary Robert Gates accused some European allies of failing to pull their weight.

In a sign that Gaddafi forces may be getting stretched, the rebels seized the town of Kikla, 150 km (90 miles) southwest of Tripoli. They also pushed several kilometers west of their Misrata stronghold to the outskirts of government-held Zlitan.