A Nato air strike has badly damaged buildings in Libyan leader Col Muammar Gaddafi's compound in Tripoli.
At least two missiles reportedly struck the sprawling Bab al-Azizia compound early on Monday. Three TV stations briefly went off the air afterwards.
The blasts were among the biggest in the capital so far, correspondents say. Nato is targeting Libyan government forces as they try to quell a revolt.
Col Gaddafi's son, Saif al-Islam, condemned the "cowardly" attack.
"I would like to say that it is possible this attack would scare young boys and girls. That's something, but we are not going to surrender or wave the white flag and we are not scared," he told Libyan state TV.
"You, Nato, are surrounded by agents, traitors and spies, while Muammar Gaddafi is surrounded by millions. So I tell you now that you are losing the battle. History has proved that no state can rely on them to win."
The BBC's Ian Pannell in Tripoli said the damaged buildings appeared to be the same ones that Col Gaddafi used to host a recent visit by an African Union peace mission.
Some officials at the scene said there had been some injuries, and state media showed patients at a local hospital receiving treatment. But others contradicted that, saying no-one had been hurt.
Reports said Libyan Television and the Jamahiriya and Shababiya TV stations were off air for about half-an-hour following the blasts.
On Sunday, forces loyal to the Libyan leader bombarded areas of the western city of Misrata, despite the regime saying it had halted attacks to allow local tribes to negotiate with rebels.
At least six people were reported killed in the latest bombardment, which reportedly hit the city centre and three residential districts.
A captured pro-Gaddafi soldier told AFP news agency that loyalist forces were losing the battle for Misrata.
"Many soldiers want to surrender but they are afraid of being executed [by rebels]," said Lili Mohammed, a Mauritanian hired to fight the insurgents.
On Sunday, Libyan Deputy Foreign Minister Khaled Kaim said the army was pausing to allow local tribes to settle the battle "peacefully and not militarily".
But Col Omar Bani, military spokesman for the rebels' Transitional National Council (TNC), said Col Gaddafi was "playing a really dirty game" in an attempt to divide his opponents.
"It is a trick, they didn't go," Col Bani said in the eastern city of Benghazi. "They have stayed a bit out of Tripoli Street but they are preparing themselves to attack again."
British Journalist James Hider, who is in Misrata for The Times newspaper, told the BBC that although pro-Gaddafi forces encircled Misrata, their forces inside the city were themselves surrounded by rebel fighters.
He said their supplies were cut off and Nato air strikes were starving the main force outside the city of supplies from elsewhere.
Mr Hider said rebels hoped they would be able to regain control of the city centre soon but did not think they would be able to defeat all the government forces until Nato strikes destroyed their biggest weaponry.
Human rights groups say more than 1,000 people have been killed in Misrata and many more wounded. Ships have been ferrying the wounded to hospitals in Benghazi.
The revolt against Col Gaddafi began in February, inspired by uprisings elsewhere in the Arab world.
Rebel leaders received a financial boost on Sunday when Kuwait announced it was giving 50m dinars (£110m, $180m) to the Transitional National Council.
Nato is carrying out air strikes against Libyan state forces under a UN mandate to protect civilians.