The crackle of celebratory gunfire still rings out across the city at night, two months after Moamer Kadhafi's fall, but the wide diffusion of weapons poses a real danger for Libya's liberated capital.

With a gun slung over his shoulder, Abdelkarim Mahmud watches as two diggers demolish a section of the six-kilometre (3.7 miles) wall that surrounds the Bab al-Aziziya compound in Tripoli, Kadhafi's former stronghold.

Dressed in combat trousers, a T-shirt and flip-flops, the 19-year-old says he was never trained to use the weapon, which he took from a dead Kadhafi soldier in the town of Misrata in March, when he joined the rebellion.

"I just took the gun and started shooting it," he told AFP.

Weapons poured into Tripoli during the revolution, with the Kadhafi regime handing out arms to its supporters and the rebels shipping in guns from outside.

Officials say they have seen boys as young as 13 brandishing Kalashnikov rifles in the middle of the night.

"There are tens of thousands of these weapons. It's a big challenge... The presence of weapons on such a wide scale definitely raises concerns," Osama al-Abed, the deputy chairman of the Tripoli municipal council, told AFP.

"We are doing all it takes to organise and to make an inventory of where the weapons are. Some of them are small rifles, some of them are medium to heavy machine guns," he added.

The nature of the problem was starkly illustrated on Friday, when a gunfight broke out in Abu Salim, a traditionally pro-Kadhafi neighbourhood not far from Bab al-Aziziya, between supporters of the ousted dictator and forces loyal to the National Transitional Council (NTC).

At least three people were killed in the fighting, which spread to other districts in Tripoli and prompted the authorities to mount a clean-up operation that included an appeal to those harbouring weapons to hand them in.

Haytem al-Amari, 25, a pro-NTC resident of Abu Salim says Kadhafi loyalists are hiding guns everywhere.

"We know what happened on Friday is going to happen again and again, until they bring the equipment to find and collect the guns. They are hiding them everywhere, under the sand, behind walls, in their gardens," he said.

Amari and his friends say they witnessed Kadhafi's sons Khamis and Seif al-Islam distributing guns in their neighbourhood at the end of August, around the time that Tripoli fell.

The fighting on Friday was the first time supporters of the old regime have taken up arms since Tripoli fell to the rebels. The authorities have insisted it was contained fairly quickly and was very limited in scope.

But another issue less easily resolved is the presence in Tripoli of numerous heavily-armed militias, or brigades, some of whom believe they played a key role in the revolution and have shown themselves reluctant to take orders from the NTC leadership.

Efforts are underway to disarm those groups, or integrate them into the army once it is formed, something Britain's visiting foreign minister William Hague described on Monday as a key challenge for Libya's new government.

Khalifa Haftar, one of Libya's top military commanders, said on Sunday that procedures were being put in place to enroll the rebels in the army, and that whoever refused to do so would have to give up his weapons.

"Collecting those weapons will take place step by step. It won't happen straightaway," he told AFP.

Other NTC officials say that for the moment, the state is simply unable to provide the security needed to persuade many Libyans to give up their guns, and that unless civilians are disarmed, future political disputes could be played out on the street.

"The people have no experience of political disagreement in Libya, so the environment is fertile" for violence, said Waheed Burshan, the NTC president in Gharyan, southwest of Tripoli.