Just three weeks after rebels backed by NATO bombers overran the capital, French President Sarkozy and the British prime minister promised in Tripoli to help hunt down Muammar Gaddafi and to hand his frozen assets to his successors.
The forces of the National Transitional Council (NTC) later said they had stormed Gaddafi's home town of Sirte, one of three main urban areas still beyond the interim government's control.
NTC fighters were facing strong resistance from loyalist fighters, especially snipers, a military spokesman said.
In Benghazi, seat of the uprising which early intervention by French and British jets helped to save from Gaddafi's army in March, Sarkozy and Cameron were treated to a rowdy welcome on "Freedom Square", shouting to be heard over a cheering crowd of hundreds -- many in the city were unaware of their arrival.
"It's great to be here in free Benghazi and in free Libya," said Cameron as he strained, rock-star hoarse, above the chants in televised scenes both men will hope play well back home.
The French president, struggling for re-election next year, beamed at grateful chants of "One, two, three; Merci Sarkozy!" while the two leaders, flanking NTC chairman Mustafa Abdel Jalil, held his arms aloft like a victorious boxer.
"France, Great Britain, Europe, will always stand by the side of the Libyan people," said Sarkozy, whom many Libyans credit with making a decisive gamble, pulling in a hesitant United States and securing U.N. backing for NATO air strikes to halt Gaddafi's tanks as they closed in to crush Benghazi.
"Your city was an inspiration to the world as you threw off a dictator and chose freedom," Cameron said, clearly enjoying the relative security to speak outdoors in Benghazi after a tight lockdown in tense Tripoli. "Colonel Gaddafi said he would hunt you down like rats but you showed the courage of lions."
Hajja, a 70-year-old swathed in the rebel tricolour, watched the two leaders with a rapture they rarely experience at home: "If we could give them anything, we would -- our lives, our souls ... But for them, we would be history."
In Tripoli, Libyan interim premier Mahmoud Jibril spoke at a news conference of "our thanks for this historic stance" taken by France and Britain to launch the West into a war that did not always look set to end well for the rebels.
Both countries offered continued military support against Gaddafi loyalists holding substantial parts of Libya as well as in hunting the former strongman and others wanted for crimes against humanity. Sarkozy said he would raise the issue with neighbouring Niger, a former French colony where some of Gaddafi's senior aides and one of his sons have sought refuge.
Sarkozy, Cameron storm Libya,