The scene in Benghazi after the opposition defeated the Libyan military. (Photo by Al Jazeera English via Flickr)

UPDATE, 4:45pm: There are reports that Col. Moammar Gaddafi's youngest son, 29-year-old Saif al-Arab Gaddafi, was killed in a NATO airstrike at his house in Tripoli.

CNN reported: "Moammar Gadhafi and his wife were in their son's house when it was targeted, spokesman Musa Ibrahim said. Both of them are in good health, according to the spokesman."

NATO and opposition forces rejected Saturday Libyan leader Muammar Gaddafi's offer for a ceasefire, saying it was too late.

In an address on state TV early Saturday, Gaddafi called for negotiations with NATO and a mutual ceasefire. But the opposition and NATO were skeptical, dismissing his offer just hours later.

"(UN Security Council Resolution) 1973 explicitly calls for an end to attacks on and abuses of civilians. The regime has announced ceasefires several times before and continued attacking cities and civilians," a NATO official said.

Gaddafi refuses to take responsibility for the conflict, blaming it on mercenaries and foreigners

"The door to peace is open," Gaddafi said, sitting behind a desk. "You are the aggressors. We will negotiate with you. Come France, Italy, UK, America, come, we will negotiate with you. Why are you attacking us?"

The leader denied any attacks on civilians and posed a challenge to NATO, asking the organization to bring him the names of 1,000 of people who had been killed by the Libyan government during the uprising.

The Guardian reports:

He [Gaddafi] said Libyans had the right to choose their own political system, but not under the threat of Nato bombings. "Why are you killing our children? Why are you destroying our infrastructure," he said.

Rebel leaders have said they will only lay down their arms and begin talks on Libya's future after Gaddafi and his sons step aside. Gaddafi has repeatedly refused to resign.

"Gaddafi’s regime has lost all credibility," said Abdul Hafidh Ghoga, vice president of the Transitional National Council, in a statement. "The people of Libya cannot possibly envisage or accept a future Libya in which Gaddafi’s regime plays any role."

Gaddafi's address came amid reports of NATO attacks in the Libyan capital of Tripoli. Government buildings were the targets of the strikes.