Attacks continued through Tuesday night and into Wednesday morning with warplanes hitting the city several times an hour. The Libyan leader's government said bombs had killed 31 people.

Saying planes were overhead and bombs were falling around him, Gaddafi spoke defiantly after strikes on his Bab al-Aziziya compound. "We only have one choice: we will stay in our land dead or alive," he said in a fiery audio address on state television.

It later showed images of what it said was a meeting between Gaddafi and tribal leaders on Tuesday.

President Barack Obama said in Washington there was significant progress in the operation and it was "just a matter of time before Gaddafi goes".

At least 31 people were killed in 60 strikes on Tripoli, government spokesman Moussa Ibrahim told reporters. His account could not be independently verified.

"How could the world sleep tonight knowing that armies of such evil are willingly and knowingly attacking a peaceful capital with 60 rockets and killing people ... while there is a way out of this. To sit down, talk and negotiate," Ibrahim said.

Reuters