Libyan military aircraft fired live ammunition at crowds of anti-government protesters in Tripoli, Al Jazeera television reported on Monday, quoting witnesses for its information.

"What we are witnessing today is unimaginable. Warplanes and helicopters are indiscriminately bombing one area after another. There are many, many dead," Adel Mohamed Saleh said.

Saleh, who called himself a political activist, said the bombings had initially targeted a funeral procession.

"Our people are dying. It is the policy of scorched earth." he said. "Every 20 minutes they are bombing."

Open gallery view Protesters in Libya during recent days' unrest in Benghazi, Libya. Credit: AP

Asked if the attacks were still happening he said: "It is continuing, it is continuing. Anyone who moves, even if they are in their car they will hit you."

No independent verification of the report was immediately available.

The protesters were reportedly heading to the army base to obtain ammunition of their own, but witnesses said the air force bombed the demonstrators before they could get there.

Clashes between protesters and security forces escalated on Monday and have spread to Tripoli, after Muammar Gadhafi's son went on state television to proclaim that his father remained in charge with the army's backing and would fight until "the last man, the last woman, the last bullet."

The protests and violence were the heaviest yet in the capital, a sign of the spread of unrest after six days of demonstrations in eastern cities demanding the end of the elder Gadhafi's rule.

Even as Seif al-Islam Gadhafi spoke Sunday night, clashes were raging in and around Tripoli's central Green Square, lasting until dawn Monday, witnesses said. They reported snipers opening fire on crowds trying to seize the square, and Gadhafi supporters speeding through in vehicles, shooting and running over protesters. Early Monday, protesters took over the office of two of the multiple state-run satellite news channels, witnesses said.

A major government building in the capital was on fire on Monday morning, a Reuters reporter said. The building is where the General People's Congress, or parliament, meets when it is in session in Tripoli.

After daybreak Monday, smoke was rising from two sites in Tripoli where a police station and a security forces bases are located, said Rehab, a lawyer watching from the roof of her home.

"The city on Monday was shut down and streets empty, with schools, government offices and most shops closed except a few bakeries serving residents hunkered down in their houses," she said, speaking on condition she be identified only by her first name.

In Libya's second biggest city, Benghazi, protesters were in control of the streets Monday after days of bloody clashes and were swarming over the main security headquarters, looting weapons, several residents said. A Turkish Airlines flight trying to land in Benghazi on Monday was forced to circle over the airport and then return to Istanbul.

Protesters in Benghazi took down the Libyan flag from above the city's main courthouse and in its place raised the flag of the country's old monarchy, toppled in 1969 in the military coup that brought Moammar Gadhafi to power, one witness said.

Libya has seen the bloodiest crackdown of any Arab country on the wave of protests sweeping the region that toppled the leaders of Egypt and Tunisia.

Since the six days of unrest began, more than 200 people have been killed, according to medical officials, human rights groups and exiled dissidents.

Gadhafi's son said his father would prevail.

"We are not Tunisia and Egypt," he said. "Moammar Gadhafi, our leader, is leading the battle in Tripoli, and we are with him."

The armed forces are with him. Tens of thousands are heading here to be with him. "We will fight until the last man, the last woman, the last bullet," he said in a rambling and sometimes confused speech of nearly 40 minutes.

He warned the protesters that they risked igniting a civil war in which Libya's oil wealth will be burned. He also promised historic reforms in Libya if protests stop.

Seif has often been put forward as the regime's face of reform. Several of the elder Gadhafi's sons have powerful positions in the regime and in past years have competed for influence. Seif's younger brother Mutassim is the national security adviser, with a strong role in the military and security forces, and another brother Khamis heads the army's 32nd Brigade, which according to U.S. diplomats is the best trained and best equipped force in the military.

The clashes in Tripoli began Sunday afternoon, when protesters from various parts of the city began to stream toward central Green Square, chanting God is great, said one 28-year-old man who was among the marchers.

In the square, they found groups of Gadhafi supporters, but the larger number of protesters appeared to be taking over the square and surrounding streets, he and two other witnesses said. That was when the backlash began, with snipers firing down from rooftops and militiamen attacking the crowds, shooting and chasing people down side streets, they said.

"We saw civilian cars with Gadhafi pictures, they started to look for the protesters, to either run over them or open fire with automatic weapons," said the 28-year-old, reached by telephone. "They were driving like mad men searching for someone to kill. ... It was total chaos, shooting and shouting."

The witnesses reported seeing casualties, but the number could not be confirmed. One, who spoke on condition he be identified only by his first name Fathi, said he saw at least two he believed were dead and many more wounded. "I could still hear gunfire after 5 A.M. this morning," he said.

Human Rights Watch has reported 332 dead since the protests began on Thursday.

After midnight, protesters took over the main Tripoli offices of two state-run satellite stations, Al-Jamahiriya-1 and Al-Shebabiya, one witness said. All the witnesses spoke on condition of anonymity because of fears of retaliation.

After daybreak Monday, Green Square and its surrounding streets were empty. Schools, government offices and most stores were shut down across the city of 2 million, the witnesses said. State TV sought to give an air of normalcy, reporting that Muammar Gadhafi received telephone calls of support from the presidents of Nicaragua and Mali. It showed footage of a crowd of Libyans said to be from the town of Zeltein chanting their support for Gadhafi in a conference hall. Gadhafi, in flowing black and brown robes, waved to the crowd with both hands. It was not clear when the scene was taking place.

Western countries have expressed concern at the rising violence against demonstrators in Libya. British Foreign Secretary William Hague said he spoke to Seif al-Islam by phone and told him that the country must embark on dialogue and implement reforms, the Foreign Office said.

In his speech, the younger Gadhafi conceded the army made some mistakes during the protests because the troops were not trained to deal with demonstrators, but he added that the number of dead had been exaggerated, giving a death toll of 84.

He offered to put forward reforms within days that he described as a historic national initiative and said the regime was willing to remove some restrictions and begin discussions for a constitution. He offered to change a number of laws, including those covering the media and the penal code.

He threatened to eradicate the pockets of sedition and said the army will play a main role in restoring order. He blamed Islamists, thugs, drunks and drug abusers and foreigners of being behind the unrest.

The rebellion by Libyans frustrated with Gadhafi's more than 40 years of authoritarian rule has spread to more than a half-dozen eastern cities.

In other setbacks for Gadhafi's regime, a major tribe in Libya - the Warfla - was reported to have turned against him and announced it was joining the protests against him, said Switzerland-based Libyan exile Fathi al-Warfali. Although it had long-standing animosity toward the Libyan leader, it had been neutral for most of the past two decades. Libya's representative to the Arab League said he resigned his post to protest the government's decision to fire on defiant demonstrators in Benghazi.

The Internet has been largely shut down, residents can no longer make international calls from land lines and journalists cannot work freely, but eyewitness reports trickling out of the country suggested that protesters were fighting back more forcefully against the Middle East's longest-serving leader.

Video footage posted on the Internet on Monday showed cars in Benghazi honking their horns in celebrations while protesters chanted, Long live Libya and Libya is all one. Several witnesses said police and security forces had disappeared from the streets and protesters were in control after heavy clashes the day before.

Youth volunteers were directing traffic and guarding homes and public facilities, said Najla, a lawyer and university lecturer in Benghazi, who spoke on condition she be identified only by her first name.

"Protesters also took over the Katiba, the city's main security headquarters, and some had looted weapons," a female resident said. "Now there is no sight of government officials, police or any presence of the government in the streets," she said.

Inside the large Katiba compound, protesters found the bodies of 13 uniformed security officers who had been handcuffed and shot in the head, then set on fire, said Ahmed Hassan, a doctor at Al Jalaa hospital who was among those who found the bodies. He said protesters believed the 13 had been executed by fellow security forces for refusing to attack protesters.

Fighting erupted Sunday in the city following funeral ceremonies for protesters killed the day before. Crowds marched down the city's highway running along the Mediterranean coast, then protesters began to attack the Katiba and police station as security forces opened fire.

In some cases, army units reportedly turned against security forces and pro-Gadhafi militias to side with the protesters. Mohamed Abdul-Rahman, a 42-year-old Benghazi merchant, said he say an army battalion chasing militiamen from a security compound. Najla, the university lecturer, said a local unit of commandos joined the protesters.

Khaled Abu Bakr, a resident of Sabratha, an ancient Roman city to the west of Tripoli, said protesters besieged the local security headquarters, driving out police and setting it on fire. Abu Bakr said residents are in charge, have set up neighborhood committees to secure their city.