The son and one-time heir apparent of Libyan leader Moammar Gadhafi, Seif al-Islam, defiantly appeared in Tripoli early Tuesday, saying his father's government still controlled the city, as rebels claimed to hold most of the capital.

Seif al-Islam presented himself to foreign journalists confined to the Gadhafi-controlled Rixos Hotel, despite earlier claims by opposition leaders and the International Criminal Court that he was in rebel hands. He then led a convoy through loyalist areas, where television footage showed him pumping his fists in the air as supporters cheered him.

Senior rebel sources also said another of Mr. Gadhafi's sons – Mohammed – escaped house arrest Monday. A third son is apparently still in detention, and Mr. Gadhafi's whereabouts are not known.

The head of the opposition Transitional National Council, Mustafa Abdel Jalil, said Mr. Gadhafi will receive a fair trial if captured and that the “real moment of victory” will be when he is taken into custody.

Jalil acknowledged that the rebels have yet to establish full control in Tripoli, where forces loyal to Mr. Gadhafi have battled rebels in scattered pockets. Opposition fighters say pro-government forces still hold 10-15 percent of the capital, including Mr. Gadhafi's Bab al-Aziziya compound.

Libyan state television remained off the air late Monday amid reports that rebels seized what had become a key instrument of government propaganda.

In addition to parts of Tripoli, pro-government forces also control at least two major cities affiliated with his tribe – Sabha, to the south, and Sirte, some 450 kilometers east of capital along the coast. U.S. military officials say government forces fired at least one Scud missile from Sirte Monday. No injuries were reported.

The rebels broke through Tripoli's outer defenses Sunday and reached the city's central Green Square, where thousands celebrated the opposition's arrival. Jubilant Libyans in the square, which the rebels have renamed Martyrs Square, tore down posters of Mr. Gadhafi and stomped on them. Until recently, the government had used the area for mass demonstrations in support of Mr. Gadhafi.

The rebel troops moved into central Tripoli with little resistance after capturing a key military base run by the government's elite Khamis Brigade and commanded by another of Mr. Gadhafi's sons.

The International Organization for Migration said it had chartered a boat to Tripoli to begin evacuating stranded migrants. The boat, which can carry 300 people, left Benghazi early Monday.

On Sunday, Libyan state television broadcast a series of defiant audio messages from Mr. Gadhafi. The Libyan leader said he would stay in the capital “until the end” to defend the city and called on supporters to help liberate it.

Mr. Gadhafi has seen the areas under his control shrink significantly in recent weeks as rebels advanced on Tripoli after six months of fighting to end his four-decade long rule. NATO warplanes have been supporting the rebels by bombing pro-Gadhafi forces under a U.N. Security Council resolution authorizing military action to protect Libyan civilians from government attacks.