Overjoyed Libyans poured into the streets of Benghazi on Thursday night to celebrate after the United Nations voted to authorise air strikes against Libyan leader Muammar Gaddafi's forces.

As news of the security council vote broke, the air in the rebel stronghold crackled with gunfire and the noise of bursts from anti-aircraft weapons reverberated off buildings along the seafront.

In the central square, protesters fell into each others' arms, embracing and some crying with delight at the news that the world body had approved the no-fly zone that rebels have pleaded for in recent weeks.

Red tracer bullets arced across the sky as preachers across Benghazi used mosque loudspeakers to chant "God is greatest, God is greatest."

Cars quickly took to the roads as the decision was announced at around midnight local time, with drivers honking their horns and passengers waving the rebels' black-red-green flag in celebration.

The crowd of a few hundred in Benghazi's central square swelled in minutes to several thousand as people converged from across the city to celebrate with their neighbours.

Many of those flooding into the square carried French flags and expressed gratitude for Paris's strong support for a no-fly zone and its decision to recognise the rebel government.

Marij Bourahim, an oil company employee, was already in the square when news of the UN vote broke.

"I was right here when it happened," he said. "I'm more than happy, it's probably the best day in my life. Now that we have this help we can fight until the last man and even to the last woman."

As he spoke, he hugged his friend Hussein Madani, a 48-year-old engineer, who also welcomed the UN decision.

"We needed the no-fly zone, but more than that we need to bomb Tripoli, Sirte and Sabha because that's where most of the Libyan army infrastructure is," he said, referring to towns under Gaddafi's control.

The mood in the square was festive, with many protesters accompanied by their children. A group even formed a conga line, and danced around in a circle.

The elation came after an evening in which Gaddafi threatened to send troops to "chase the traitors from Benghazi" within hours.

But by 3.00 am local time (0100 GMT) there was no sign of the promised assault, and despite several loud explosions followed by anti-aircraft fire, no aircraft were spotted over the city.

In the square, Saad, who did not give his last name, said people were no longer afraid of Gaddafi's forces, which have moved swiftly in recent days to retake rebel territory in Eastern Libya.

"I'm not scared, we've been scared for 42 years, it's more than enough," he said, standing next to his sons, 19-year-old Faraj and 12-year-old Yussef.

"Now that you are going to help us, I can send my 12-year-old son and he can fight Gaddafi!"

Even before the UN Security Council decision was announced, the mood in Benghazi was defiant, with people mocking Gaddafi's threats to overrun the city.

"He is drowning, he cannot do anything to these people around here," said Monem Zelitny, 55.

"These people are determined to fight to the last drop of blood. They don't have a choice," he said. "Nobody's afraid. You live only once and you die only once, either you live free or die... We do not surrender."