Nato air strikes have rattled the Libyan capital with clusters of bombing runs believed to have targeted the outskirts of Tripoli.
At first, the intensity of the attacks suggested a return to the heavy Nato bombardment which hit military installations across the capital on Tuesday and flattened major buildings in leader Muammar Gaddafi's sprawling compound in the centre of the city.
By nightfall, a total of 14 air attacks had been carried out, considerably fewer than Tuesday. There were eight explosions in a first series of strikes today and, hours later, the sound of six more air strikes boomed in the distance. Government officials did not say what had been targeted.
The strikes are in support of a four-month-old rebel uprising which seeks to push Gaddafi from power after four decades. Rebels have taken control of swathes of eastern Libya, although fighting has since become a stalemate even with Nato support.
Gaddafi shows no signs of ceding power under the building pressure of the Nato strikes, despite repeated attacks on his compound, government buildings, military radar emplacements and other army installations.
But the chief of the US CIA, Leon Panetta, said in evidence before the Senate that the Nato military operation, strong economic sanctions, and enforcement of the no-fly zone are putting tremendous pressure on Gaddafi. US President Barack Obama has named Mr Panetta to take over as Defence Secretary this summer.
Among other signs of building pressure, US Secretary of State Hillary Clinton said that there are "numerous and continuing" overtures by people close to Gaddafi to negotiate his departure from power.
Speaking to reporters after an international conference on Libya in the United Arab Emirates, she said proposals from "people close to Gaddafi" presented to unspecified countries included the "potential for a transition". But she said she could not predict if they would be accepted.
Fighting on the ground between Libyan government forces and the rebels largely died down after the Nato strikes began. The Western alliance took to the skies over Libya under a UN resolution which allowed Nato flights to protect civilians. What began as a no-fly zone quickly evolved into strong attacks on the regime.
However, on Wednesday Gaddafi forces renewed their shelling near the western city of Misrata, killing 10 rebel fighters. Misrata is one of the few footholds rebels have in western Libya.