The clashes appeared to be isolated and involve only dozens of pro-Gaddafi fighters, but it was the first sign of armed resistance to the NTC in Tripoli since its rebel brigades seized the city and ended Gaddafi's 42-year rule in August.

Hundreds of NTC fighters in pick-up trucks shouting "Allahu Akbar" (God is greatest) careered toward the Abu Salim neighborhood, a repository of support for Gaddafi, and the two sides exchanged automatic and heavy machinegun fire.

The fighting in Tripoli coincided with prolonged battles in Sirte, where NTC forces are battling pro-Gaddafi fighters holed up in a small area of Gaddafi's home town.

Since he went into hiding after rebel forces captured Tripoli on August 23, Gaddafi has released a number of audio recordings calling on loyalists to fight back.

The NTC fighters were met by volleys of machinegun fire as they went from house to house searching for remaining pro-Gaddafi gunmen. Shooting died down later in the afternoon.

A spokesman for the NTC in the eastern city of Benghazi dismissed Gaddafi's armed supporters in Tripoli as a "fifth column" trying to destabilize the country.