The son and heir apparent of Libyan leader Moammar Gadhafi, Seif al-Islam, resurfaced free and defiant early Tuesday a day after rebels claimed to have captured him, boasting in a bizarre reappearance that his father's loyalists still control parts of Tripoli and would crush the rebellion.

Seif al-Islam's sudden _ even surreal _ arrival at a Tripoli hotel where foreign journalists are staying threw the situation in the capital into confusion. It underlined the potential for Gadhafi, whose whereabouts remain unknown, to lash back even as his grip on power seemed to be slipping fast.

Rebels say they control the large majority of Tripoli, but on Monday they were still fighting pockets of fierce resistance from regime loyalists firing mortars and anti-aircraft guns. Rebel spokesman Mohammed Abdel-Rahman, who was in Tripoli, said the "danger is still there" as long as the elder Gadhafi remains on the run. He warned that pro-Gadhafi brigades are positioned on Tripoli's outskirts and could "be in the middle of the city in half an hour."

The rebel leadership seemed stunned that Seif al-Islam was free. The leadership's spokesman, Sadeq al-Kabir, had no explanation and could only say, "This could be all lies."

He could not confirm whether Seif al-Islam escaped rebel custody, but he did say that another captured Gadhafi son, Mohammed, had escaped the home arrest that rebels had placed him in a day earlier. On Monday, the rebels had said Seif al-Islam was captured, but did not give details on where he was held. The Netherlands-based International Criminal Court _ which indicted Seif al-Islam and his father _ had confirmed his capture.

Seif al-Islam, with a full beard and wearing an olive-green T-shirt and camouflage trousers, turned up early Tuesday morning at the Rixos hotel, where about 30 foreign journalists are staying in Tripoli under the close watch of regime minders.

Riding in a white limousine amid a convoy of armored SUVs, he took reporters on a drive through parts of the city still under the regime's control, saying, "We are going to hit the hottest spots in Tripoli." Associated Press reporters were among the journalists who saw him and went on the tour.

The tour covered mainly the area that was known to still be under the regime's control _ the district around the Rixos hotel and nearby Bab al-Aziziya, Gadhafi's residential compound and military barracks. The tour went through streets full of armed Gadhafi backers, controlled by roadblocks, and into the Gadhafi stronghold neighborhood Bu Slim.

At Bab al-Aziziya, at least a hundred men were waiting in lines for guns being distributed to volunteers to defend the regime. Seif al-Islam shook hands with supporters, beaming and flashing the "V for victory" sign.

"We are here. This is our country. This is our people, and we live here, and we die here," he told AP Television News. "And we are going to win, because the people are with us. That's why were are going to win. Look at them _ look at them, in the streets, everywhere!"

When asked about the ICC's claim that he was arrested by rebels, he told reporters: "The ICC can go to hell," and added "We are going to break the backbone of the rebels."

In Benghazi, the de facto rebel capital hundreds of miles east of Tripoli, the head of the rebel National Transitional Council said the rebels have no idea where Gadhafi is or whether he is even in Tripoli.,

"The real moment of victory is when Gadhafi is captured," Mustafa Abdel-Jalil said. An Obama administration official said the U.S. had no indication that Gadhafi had left Libya.

President Barack Obama said the situation in Libya reached a tipping point in recent days after a five month NATO-led bombing campaign. However, he acknowledged that the situation remained fluid and that elements of the regime remained a threat.

The Obama administration official said the U.S. believes 90 percent of the capital is under rebel control, while regime loyalists still control Sirte and the southern city of Sebha. The official spoke on the condition of anonymity because the official was not authorized to speak publicly.

Gadhafi's forces remained active, firing off a short-range Scud missile Monday near Sirte, Gadhafi's hometown and one of the few remaining cities still under his control, said U.S. military officials, who spoke on condition of anonymity to discuss military operations. It was unclear where the missile landed or if anyone was hurt.

It was only the second Scud missile fired during this year's conflict. On Aug. 15, Libyan government forces launched one near Sirte that landed in the desert outside Brega, injuring no one.

NATO vowed to keep up its air campaign until all pro-Gadhafi forces surrender or return to their barracks. The alliance's warplanes have hit at least 40 targets in and around Tripoli in the past two days _ the highest number on a single geographic location since the bombing started in March, NATO said.

A day after the rebels rode into the city of 2 million, the situation remained volatile. Even though rebels claimed they were in control of most of Tripoli, they still appeared to be on the defensive, ducking for cover during frequent clashes with regime fighters. Stores were shuttered and large areas were lifeless, including the old gold market, in the past a draw for tourists.

Throughout the day, the rebels sent reinforcements to the city from the north, south and southeast, and a rebel field commander said more than 4,000 fighters were part of the final push to bring down the regime. Rebels manned checkpoints on the western approaches to the city Monday, handing out candy to motorists and inquiring about their destinations.

Intense gun battles erupted throughout the day. At Bab al-Aziziya compound, government tanks emerged from the complex and opened fire at rebels trying to get in, according to the rebel spokesman Abdel-Rahman and a neighbor.

Around midday Monday, rebel fighters took over a women's police college near the Mediterranean and declared that they would set up their new headquarters there.

"We are going to protect the city of Tripoli from all attacks and threats," fighter Munir al-Ayan said after kneeling and kissing the ground in the compound.

"I was bowing down to the Almighty God who helped us get rid of this brutal dictator," he later explained.

But the rebels' optimistic mood of the morning quickly changed. By mid-afternoon, the college came under heavy fire. Snipers from nearby high-rises aimed at motorists speeding by. An anti-aircraft gun pounded the compound, creating a deafening noise. A handful of rebel fighters inside seemed jumpy and unsure what to do.

Gadhafi loyalists also launched attacks in two other areas of Tripoli, said Ashraf Hussein, a rebel fighter who sat pressed against an inner wall of the compound for safety.

Drivers trying to evade sniper fire ducked into side streets, or stopped at rebel checkpoints to find out whether the next stretch was safe. Booms of mortar rounds and small rockets reverberated across the city, mixed with battle cries of "God is great."

Later Monday, another battle erupted around a school where rebels and journalists had set up camp. Rebels fired small rockets, and Gadhafi troops responded with mortar shells.

Still, revelers flocked to Green Square, the symbolic heart of the fading Gadhafi regime. They flashed the "V" for victory sign and motorists circled the plaza, honking horns and waving rebel flags.

"We came out today to feel a bit of freedom," Ashraf Halati, a 30-year-old Tripoli resident, said as he and four of his friends watched several hundred people celebrating at Green Square. "We still don't believe that this is happening."

Late Sunday night, rebels took over Green Square, which they have been calling Martyrs Square, restoring the name it had before Gadhafi's regime took power more than four decades ago. Google's map of Tripoli has already adopted the new name. The opposition also took up the pre-Gadhafi flag of Libya as their own at the start of their uprising six months ago.

The Rixos hotel where foreign journalists are staying also remained under the control of Gadhafi forces, with two trucks loaded with anti-aircraft machine guns and pro-regime fighters and snipers posted behind trees.

About 30 journalists remained in the hotel where armed pro-Gadhafi youths kept a close eye on them and did not allow to them to exit the building. Journalists began to worry that food, water and fuel that powers the hotel's generator were running low.

Some of the journalists attempted to walk out of the hotel but were met with hostility by the armed guards, who said they were put there to "protect" them. Journalists said they felt like they were being held hostage.

Outside of Tripoli, almost all of eastern and western Libya is now under rebel control. The east of the country from the Egyptian border to Benghazi fell into rebel hands at the beginning of the uprising. In the weeks leading up to Sunday's lightning advance on Tripoli, the rebels consolidated control of the western Nafusa mountain range near the border with Tunisia. It was from there they staged the run on the capital. Most of the rest of the country was quickly falling into their hands.

The city of Sirte, Gadhafi's hometown to the east of Tripoli, was the most important loyalist bastion to remain fully under his control.

On Monday, the city was without power and full of heavily guarded Gadhafi checkpoints, said Hassan al-Daroui, an official with the rebel council in Benghazi who was in touch with people there by satellite phone. Many people there were not even aware that rebels had pushed into the capital, 250 miles (400 kilometers) to the northwest, he said.

On Saturday rebels said they gained control of the oil refineries and airport at the oil terminal of Brega, on the road heading out of Benghazi west toward Tripoli.

The rebels' startling breakthrough on Sunday, after a long deadlock in Libya's 6-month-old civil war, was the culmination of a closely coordinated plan by rebels, NATO and anti-Gadhafi residents inside Tripoli, rebel leaders said. Rebel fighters from the west swept over 20 miles (30 kilometers) in a matter of hours, taking town after town and overwhelming a major military base as residents poured out to cheer them. At the same time, Tripoli residents secretly armed by rebels rose up.

Libyan state television was off the air Monday amid reports it had been seized by rebels.

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Associated Press writers David Stringer in London and Slobodan Lekic in Brussels contributed to this report.