Col Gaddafi's second son and heir apparent appeared on television late in the evening to say there would be "rivers of blood" and that Libya was on the brink of a civil war that would burn its oil wealth.
"Our spirits are high and the leader Muammar Gaddafi is leading the battle in Tripoli, and we are behind him as is the Libyan army," he said. "We will keep fighting until the last man standing, even to the last woman standing...We will not leave Libya to the Italians or the Turks."
But he admitted that "civilians are driving tanks in Benghazi" and though he said only 84 people had died showed he was aware of the extent of the uprising.
"This is an opposition movement, a separatist movement which threatens the unity of Libya," he said. "We will take up arms, we will fight to the last bullet. We will destroy seditious elements. If everybody is armed, it is civil war, we will kill each other."
Opponents of the Gaddafi regime were in control of parts of Libya's second city Benghazi having driven back security forces who fired on them with high-velocity sniper rifles, machine guns and even anti-aircraft artillery.
There were less violent clashes in Tripoli, though there were also reports of gunfire and tear gas there as demonstrators gathered near Green Square and hurled stones at police. One protester told the al-Jazeera network they were chanting at the leader: "Where are you? Where are you? Come out if you're a man."
Human Rights Watch says that at least 233 people have died since last week in the unrest, which has spread from the eastern provinces. It said at least 60 people died in Benghazi yesterday, 50 deaths having been recorded at Al-Jalaa Hospital and ten more at 7 October Hospital.
The city was described to diplomats as a "war zone" by a senior regime official.
"Troops including mercenaries are being sent there by plane," diplomats said they were told. "The fighting is intensifying.
"Lots of people are being killed, including members of the security forces.
The figures are certainly above 200, with many thousands more injured across the country." Benghazi is 600 miles east of Tripoli, and has always been more hostile to Col. Gaddafi's regime than other parts of the country.
According to a local lawyer, members of an elite army unit known as "The Thunderbolt" defected to the protesters and overwhelmed a force belonging to the separate Republican, or Praetorian Guard.
"They are now saying that they have overpowered the Praetorian Guard and that they have joined the people's revolt," the lawyer, Mohamed al-Mana, told Reuters by telephone.
Fighting has also broken out in the eastern cities of Al-Bayda, Ajdabiya, Darnah, and Tobruk, with eye-witnesses reporting Molotov cocktails, rifles and even antique Arabic sabres being used by demonstrators.
In Darnah, a group of Islamists seized an arms depot, and were holding civilians and soldiers there hostage.
Protestors in Ajdabiya claimed that it was a 'Free City' after the headquarters of Gaddafi's Revolutionary Committee were burned down on Friday, along with 14 other buildings.
There were also reports of protesters clashing with the authorities in the town of Misrata, just 120 miles to the east of Tripoli, and later in Tripoli itself.
The breakdown of the authorities' control in Benghazi, where the armed forces were reported to have retreated to their command centre and to be firing indiscriminately on protesters surrounding it, was clear from videos being posted on the internet in greater numbers than before.
One showed the body of a man in blue police fatigues being carried away by demonstrators, who can be heard discussing whether he was one of the "African mercenaries" said to have been recruited by Col. Gaddafi to defend himself. The corpse had black rather than Arab features, though that does not necessarily mean he is not a Libyan citizen.
A regional medical coordinator told The Daily Telegraph bodies were piling up in hospitals. "Tanks and helicopter gunships full of foreign mercenaries are fighting gangs of demonstrators," he said. "At least one dead man had been hit by an anti-aircraft missile, while other bodies are riddled with heavy machine gun fire."
One Libyan journalist claimed that a group of women and children jumped to their deaths from a bridge in Benghazi to escape the "mercenaries".
He said: "Some of these mercenary shock troops have been killed or captured, and some of them are said to on the equivalent of around 500 dollars a day. These killers are coming from countries like Chad.
"They're vicious. People are so terrified of them that they've been doing everything possible to get away. Women and children were seen jumping off the Giuliana Bridge in Benghazi to get away. Many of them were killed by the impact of hitting the water, while others were drowned."
Rumours that mercenaries were being recruited by the government forced Libya's ambassador to India to resigned in protest. Ali al-Essawi told the BBC that he could not support his government's violent crackdown on demonstrators calling for the ouster of Libyan leader Muammar Gaddafi.
The BBC, on its Arabic service website, said Essawi accused the government of deploying foreign mercenaries against the protesters.
Saif al-Islam Gaddafi said his father, who has only briefly appeared on state television in a pro-government rally, remained in the country and was backed by he army.
He offered to put forward reforms within days that he described as a "historic national initiative". He said the regime was willing to remove some restrictions and discuss the constitution.
In his televised statement he acknowledged the army made mistakes during the protests, but denied reports that hundreds were dead.
Many of the 3500 British people living in Libya are preparing to leave. The Foreign Office said 50 Britons living in the east of the country were being helped to find "a place of safety".
Col. Gaddafi has briefly appeared on state television in a pro-government rally, but has otherwise remained silent.
"Gaddafi's fear is that eastern cities will fall, and a full-scale revolt will reach Tripoli," said Omar, 24, a civil servant in Benghazi.
Amid reports that large numbers of soldiers have defected to the protesters, Col. Gaddafi's third son, Saadi, was said to be coordinating the forces ranged against the protestors.