With rebel fighters celebrating in the streets of Tripoli on Tuesday, opposition leaders in this eastern Libyan city now face tough questions about how they will guide the country through what is expected to be a tumultuous transition.

Some observers have begun to question whether the rebels — ostensibly led by the Benghazi-based Transitional National Council — are up to the task of restarting a failed economy after six months of war, restoring peace, and assuring Libyans and foreign benefactors that they are capable of leading the country.

The rebels have been plagued by infighting almost from the moment they first rose to challenge Moammar Gaddafi, and the friction has not subsided despite celebrations on Tuesday as rebel fighters stormed the leader’s compound in Tripoli.

The top rebel commander was assassinated last month in a case that remains unsolved but that has spurred furious accusations among various rebel factions. When an investigation of the killing bogged down, rebel council chief Mustafa Abdel Jalil dismissed his cabinet.

Concerns about the rebel leadership deepened on Tuesday after Gaddafi’s most influential son, Saif al-Islam Gaddafi, appeared in public despite rebel claims that he had been captured.

“The Transitional National Council is not without its problems,” said Geoff Porter, an analyst with North Africa Risk Consulting. “Its decision-making process is unpredictable and far from transparent. . . . This suggests that future dealings with the council are going to be prickly, challenging and uneven.”

The opposition in Libya is a patchwork of militias, defected soldiers and tribal fighters. Cities across the country have formed their own councils, rebel forces and leadership structures to fill the void as Gaddafi’s forces have crumbled. Communication has been difficult and commanders from other cities, such as Misurata, have been frustrated by decisions made by officials in Benghazi.

But the rebel council is the only body organized enough to take control in a post-Gaddafi era.

The council has gained international recognition from many countries, including the United States. Its members were instrumental in helping to persuade the U.N. Security Council to implement a no-fly zone and to authorize the NATO bombing campaign that has devastated Gaddafi’s defenses. The rebel council also has been drumming up financial support. On Tuesday, the Turkish foreign minister announced that his government will provide the rebels with $300 million, including a $100 million loan, to help build a political system.

The 45 council members are a mix of defected ministers from the Gaddafi government, academics, dissidents and returning exiles. They plan to expand the council to up to 100 members to include defected experts from the Gaddafi government who can help run the country during the transition, according to a Western diplomat in Benghazi.

“Among the most important priorities is to restart the economy. Oil production has stopped, and security is about to be reduced to nil,” said the diplomat, who spoke on the condition of anonymity because he was not authorized to discuss the situation.

Despite TNC assurances that the next government will represent all Libyans equally, U.S. officials and Middle East experts acknowledge deep divisions within the rebel alliance that could complicate efforts to rebuild the country. They say the rebel soldiers who now occupy the capital represent several highly diverse groups united only by a common desire to defeat Gaddafi.

The leaders of the TNC hail mostly from eastern Libya, an area that is culturally distinct from the capital region where a quarter of all Libyans live. And many of the military successes in recent weeks have been achieved by yet another group, ethnic Berbers from the mountains south and west of Tripoli. Overlying the ethnic and tribal divisions are ideological fault lines separating secularists from Islamists, U.S. officials and Middle East experts say.

“Some of these groups are fighting for their own causes,” said Bayless Parsley, a North Africa specialist for Statfor, a private company that provides intelligence assessments of security risks for corporations and governments. “They are pledging allegiance to the TNC at the moment and expressing a desire for unity.”

But once Gaddafi vanishes as a unifying force, there will be an increasing potential for strife and even civil war as armed groups jockey for control over the spoils, Parsley said.

Gaddafi has long exploited ethnic and tribal divisions to consolidate his rule and excuse brutal tactics. At the start of the uprising, Saif al-Islam Gaddafi used the fear of division to justify the bloody crackdown carried out by Gaddafi forces. In the six months since Libya’s uprising, there have been revenge killings against regime loyalists but few signs of ethnic and tribal warfare in the country.

Concerns about the potential for fighting among the rebel factions have preoccupied U.S. strategists for months, and partly explain U.S. hesitancy to release billions of dollars in frozen Libyan assets, the experts say. White House officials have come to see the frozen assets as leverage — a means of keeping the fractious and quarrelsome rebels together, said Michele Dunne, a former Middle East specialist at the State Department and the National Security Council.

“The TNC will need those billions of dollars to be turned over, but that won’t happen unless there is some confidence of the part of the U.S. government and others that those funds will be turned over to a government that is peaceful,” said Dunne, now director of the Atlantic Council’s Rafik Hariri Center for the Middle East.

On Tuesday night, council spokesman Mahmoud Jibril announced the formation of a security council that will try to stabilize the country. He called for unity, not vengeance, and promised that no one would be marginalized in a new Libya.

Quoting the Muslim prophet Muhammad, he said, “We went from the smaller jihad to the larger jihad, which is the struggle against ourselves.”

He added: “The whole world,” is waiting to see: “Are we up to the responsibility of this revolution?”

On Wednesday, the office of French President Nicolas Sarkozy announced that Jibril would travel to Paris later in the day to meet with Sarkozy to discuss “the situation in Libya and the international community’s actions to support the political transition to a free and democratic Libya,” the Associated Press reported.

With rebels in almost complete control of Tripoli, a delegation of key ministers from the council is planning to move to the capital in the coming weeks.

“This is a very symbolic act to show that the national council is here to help the people working [in Tripoli],” said Fathi Baja, a council member who will join the delegation. “What we are concerned about now is to finish the liberation of Libya.”

Warrick reported from Washington.