— Fugitive leader Moammar Gaddafi vowed Thursday to wage a “long fight” to regain the power he seized 42 years ago to the day, calling on his supporters to set the country ablaze to defeat NATO and its Libyan allies.

A pair of defiant audio statements from Gaddafi, broadcast by a Syria-based television channel that has become the mouthpiece of his crumbling regime, appeared to set back the rebel leadership’s hopes for a peaceful surrender of his remaining strongholds.

With Gaddafi loyalists still in control of his home town of Sirte, rebels appeared to back away Thursday from their threat to attack the town this weekend if the holdouts did not surrender.

In a tacit acknowledgment of the formidable military challenges still confronting the rebels, Secretary of State Hillary Rodham Clinton said Thursday that it was too early to discuss halting the NATO air campaign, which has been underway since March.

“We must see our military mission through to its conclusion,” Clinton said after meeting in Paris with leaders of the rebels’ Transitional National Council. “Coalition military operations should continue as long as civilians remain under threat of attack.”

Clinton was in France for talks with officials from more than 60 countries and international organizations on how to help Libya’s new leaders meet urgent needs and begin forming a functioning government. The day of meetings began with the formal dissolution of the Libya Contact Group, an international coalition formed five months ago to assist the rebels. It is being re-branded “Friends of the New Libya.”

Despite his messages, Gaddafi’s whereabouts remained a mystery, with rebels leaders saying he could be in the desert between Sirte, 278 miles east of the capital, and Bani Walid, a town 100 miles southeast of Tripoli. An Algerian newspaper put him in the far western Libyan town of Ghadamis, near the borders with Algeria and Tunisia.

Since the fall of the capital last week, NATO has concentrated its firepower on Sirte, carrying out airstrikes as rebels advanced toward the Mediterranean coastal city from the east and west. NATO warplanes have hit dozens of military vehicles, several command posts and military facilities, observations posts, missile and rocket launchers, and an antenna.

Rebel leaders had set a Saturday deadline for Gaddafi loyalists in Sirte and other pockets in the south and center of the country to surrender. But Col. Ahmed Bani, a spokesman for the rebel military, said Thursday that Gaddafi’s fighters in Sirte would have until Sept. 10 to lay down their weapons, giving the town’s residents time to understand the new reality in Libya.

Much of the country — including the capital, Tripoli — is controlled by the rebels, leaving Sirte isolated, save for a desert corridor leading from the town to Bani Walid and on to Sabha, about 480 miles south of Tripoli. Sirte has no electricity or water service, and it is unclear whether residents know that Gaddafi has lost control of most of the country, Bani said.

But another top rebel official would not confirm the deadline extension, underscoring the divide within the rebel leadership over how to press ahead against the Gaddafi holdouts.

Mustafa Sagazly, deputy interior minister in the rebel council, said he had not been informed about any such extension.

“Time is on our side, and as time passes by, we are getting stronger and they are getting weaker,” Sagazly said. “We can be patient a few more days, but we have to end this war situation.”

In Tarhouna, southeast of Tripoli, a captured guard from the elite brigade commanded by Gaddafi’s son Khamis, said Thursday that he had seen Gaddafi last Friday.

Seventeen-year-old Abdulsalaam Tahara, in a yellow Benghazi Sailing Club T-shirt, said he saw Gaddafi, dressed in a green shirt, pants and a turban, leave a Tripoli suburb with his wife, Safia, daughter Aisha and son Saif al-Islam in a convoy of white Toyota Land Cruisers heading south.

Gaddafi’s wife, daughter, and two other sons — Hannibal and Mohammed — and their children crossed the land border into Algeria on Monday, but Algerian officials have said that they will not give refuge to Gaddafi himself.

Col. Abdul Razzaq al-Nadouli, a rebel commander at the Tarhouna military base, said he had received repeated, reliable information from fleeing Bani Walid residents that Saif al-Islam and Mutassim Gaddafi, another son of the autocrat and the feared national security chief in the Gaddafi government, were in Bani Walid as recently as Wednesday.

In his statements on the Syrian-based al-Rai channel, Gaddafi warned that Libya will “turn into hell.”

“Stand up to them with bullets,” he told his supporters on the 42nd anniversary of the military coup that brought him to power. “Continue to fight from city to city, valley to valley, mountain to mountain.”

In a second broadcast late Thursday, he described NATO as “imperialists” and promised that Libya would not become a colony and allow the West to steal the country’s oil and water.

“We are ready for a long war, a very long war until we beat you,” Gaddafi said.

In a sign of Gaddafi’s further isolation, Russia’s Foreign Ministry posted a statement on its Web site Thursday saying that the country was recognizing the rebel council as Libya’s legitimate government, a move aimed at protecting Russia’s economic interests in the oil-rich nation.

During Gaddafi’s four decades in power, Russia forged arms, energy and infrastructure deals with Libya that were worth billions of dollars.

Russia’s announcement leaves China as the only permanent member of the U.N. Security Council that does not recognize the rebel council as Libya’s legitimate governing body. Beijing also has billions of dollars in business investments in Libya that are at risk.

Staff writer Joby Warrick in Washington and correspondents Simon Denyer in Tarhouna and Michael Birnbaum in Cairo contributed to this report.