Tripoli, Libya: A series of NATO airstrikes rocked the Libyan capital before dawn on Sunday, sending up huge plumes of smoke over the city after hitting what Libyan state television said were civilian and military targets.

As the explosions struck just after midnight, a string of dull rumbles could be heard and flashes seen to the city's east, as sporadic tracers of anti-aircraft fire arced into the night sky.

State television said the strikes targeted the suburb of Tajoura. The distant rumbling of blasts continued for at least an hour, suggesting some kind of facility with explosive materials had been hit.

NATO fighters have been carrying out airstrikes against Libyan military targets as part of a U.N.-mandated operation to protect civilians. The blasts come after three days of defiant speeches by Libyan leader Moammar Gaddafi.

Gaddafi's audio address

Gaddafi said Saturday afternoon that his country will never surrender in the face of assaults by rebels and a NATO air campaign. In an audio address directed at the city of Zawiya where thousands demonstrated their support, Gaddafi promised that Libya would keep fighting.

"After we gave our children as martyrs, we can't backtrack, or surrender or give up or move an inch," he said, his voice booming over loudspeakers in the center of town.

"Rest assured in your tombs, our martyrs, we will not betray you ever."

The speech was Gaddafi's third in as many days, each addressing inhabitants of a town under his control, while thousands chanted their support for the country's leader of the past 41 years.

In his speech, also broadcast on national television, Gaddafi said the NATO airstrikes on Libya must stop to save civilian lives.