The regime of Libyan leader Muammar Gaddafi is facing its biggest threat since it took over Libya 41 years ago as the death toll of the unrest gripped the country over the past seven days hit 400.

Dubai-based Al-Arabiya TV, citing eyewitnesses, said deadly clashes in the Libyan capital of Tripoli claimed the lives of 160 people on Monday.

It said the Libyan forces hurled protesters in Tripoli with hand grenades in a last ditch to keep the regime of Gaddafi alive.

The Libyan air force bombed protesters in the capital of Tripoli while they were on the way to a base belongs to the army, it added.

In a televised speech, Libyan leader Muammar Gaddafi's son Seif al-Islam warned that his father, in power for 41 years, will fight to the end and he would never give up. "We will fight to the last bullet to the last soldier," Saif al-Islam said.

But he said on Monday that a commission will be tasked to investigate the latest wave of protests and unrest that swept the country over the past days, Libya's state TV said.

Seif al-Islam said he has set up the commission which will be headed by a Libyan judge and include members of Libyan and foreign human rights groups.

Security forces and pro-Gaddafi militia looted banks and other government institutions in Tripoli, and protesters had broken into several police stations and wrecked them.

Protesters in Tripoli have ransacked the headquarters of state television overnight and set the government buildings on fire.

Fighting has also broken out in the eastern cities of Al-Bayada, Ajdabiya, Darnah, and Tobruk.

Inspired by streets-born uprisings that had swept Tunisia and Egypt and forced their leaders to step down, thousands of Libyans have started a string of protests against Gaddafi.

A host of Muslim scholars in Libya issued a fatwa (a religious edict) to urge all Muslims to join the protests against the Libyan leadership, Al-Jazeera TV reported.

The so-called Network of Free Ulema of Libya, grouping 50 preachers, said that all Muslims have a religious obligation to rebel against the regime of leader Muammar Gaddafi.

Libya's permanent representative to the Arab League, who resigned over a heavy-handed security crackdown on protesters, said a number of Tribal chieftains will gather in Tripoli tonight to muster a support for falling Gaddafi. "They will gather to end the regime," Abdel Moneim al-Honi told Al-Jazeera TV.

Al-Honi said the chief of the Libya army is now under house arrest.

"I have confirmed information say Libyan army chief General Abu- Bakr Yunis Jabil is now under house arrest," he said.

But Libya's official TV said that security forces are now targeting dozens of rioters and those who incite violence, and urged people to cooperate with the operation.

The TV stopped short of providing more details, but it urged all citizens to help the security forces to restore security in the country which has been hit by a wave of protests, the worst since Gaddafi took power more than 40 years ago.