A view of a building destroyed during a dawn NATO air raid on the capital Tripoli, on April 30, 2011, that targeted the Civil Society Council building and destroyed an adjoining school for children with Downs Syndrome. AFP PHOTO/MAHMUD TURKIA 

A NATO raid killed Libyan President Col Muammar Gaddafi's youngest son and three grandchildren but the Libyan strongman escaped unhurt in what a regime spokesman on Sunday said was a deliberate attempt to assassinate him.
The house of Seif al-Arab Gaddafi, 29, "was attacked tonight with full power," government spokesman Mussa Ibrahim told reporters, announcing the deaths from Saturday night raids.
NATO said it had targeted a command and control centre.
The Libyan leader and his wife were in the building but were not harmed, Ibrahim said, calling the strike "a direct operation to assassinate the leader of this country."
"The leader himself is in good health; he wasn't harmed. His wife is also in good health; she wasn't harmed, (but) other people were injured," he added.
Ibrahim later said intelligence on Gaddafi's whereabouts appeared to have been "leaked," adding: "They knew about him being there, or expected him for some reason."
The United States avoided comment on the reported deaths.
"We got calls from Libyans saying someone big was hit," a senior US administration official told AFP late on Saturday on condition of anonymity. "But as to who, I have only the same reports as you do."
Gaddafi also lost an adopted daughter in a US air raid in 1986.
NATO said it had staged air strikes in Tripoli but did not confirm the Libyan claims, and there was no immediate confirmation of the deaths. At least three missiles were heard exploding earlier as warplanes flew overhead.
A NATO statement said it continued precision strikes against Gaddafi regime military installations in Tripoli overnight, "including striking a known command and control building in the Bab al-Aziziya neighbourhood shortly after 1800 GMT Saturday evening."
Automatic gunfire, apparently in mourning, echoed across Tripoli and state TV showed flag-waving demonstrators it said were mourning Seif al-Arab's death.
In the rebel capital of Benghazi, overjoyed rebels fired rockets, Kalashnikovs and anti-aircraft guns and set off TNT for more than half an hour, rocking the eastern Libyan city with sustained gunfire and explosions.
"They are so happy that Gaddafi lost his son in an air strike that they are shooting in celebration," said Colonel Ahmed Omar Bani, military spokesman of the Libyan opposition Transitional National Council (TNC) there.
Earlier, Ibrahim took journalists to a heavily damaged house in Tripoli, hinting but not explicitly indicating this was the one in which Gaddafi's son had died.
Twisted reinforcing steel bars protruded from blasted concrete in and around the structure. Part of the roof had caved in, walls had collapsed, and a thick layer of dark grey dust covered the grounds.
Given the scale of the destruction, it appeared improbable anyone inside could have survived.
NATO vowed to stage more strikes, although the commander of Operation Unified Protector stressed that "we do not target individuals."
"All NATO's targets are military in nature and have been clearly linked to the... regime's systematic attacks on the Libyan population and populated areas," said Lieutenant General Charles Bouchard.
The statement said the raids would continue until all attacks and threats against civilians had ceased and until all of Gaddafi's forces, "including his snipers, mercenaries and paramilitary forces have verifiably withdrawn to their bases, and until there is full, free and unhindered access to humanitarian aid to all those in Libya who need it."
In a Saturday speech on state television, Gaddafi said NATO "must abandon all hope of his departure."
"I have no official functions to give up: I will not leave my country and will fight to the death," he said.
But he added a conciliatory note: "We are ready to talk with France and the United States, but with no preconditions.
"We will not surrender, but I call on you to negotiate. If you want petrol, we will sign contracts with your companies -- it is not worth going to war over.
"Between Libyans, we can solve our problems without being attacked, so pull back your fleets and your planes," he told NATO.
His call was dismissed by the TNC, which has shaped itself into a parallel government in Benghazi, and by NATO.
"The time for compromise has passed," TNC vice chairman Abdul Hafiz Ghoga said. "The people of Libya cannot possibly envisage or accept a future Libya in which Gaddafi's regime plays any role."
And in Brussels, a NATO official said: "We need to see not words but actions."
The regime has threatened to attack any ships trying to enter the rebel-held port of Misrata, after tanks launched an assault on the city east of Tripoli.
Misrata's port is a crucial conduit for humanitarian aid to the city of half a million, which Gaddafi's forces have been trying to capture for more than seven weeks.