Fighting was also heard in the early hours in the south of the capital where there were exchanges of heavy weaponry and automatic rifle fire.
Rebel leaders had earlier warned that pockets of resistance remained despite most of Kadhafi's defenders vanishing during the rebels' lightning charge through Tripoli on Sunday. The whereabouts of Colonel Kadhafi were unknown on Monday but one of his sons, Seif al-Islam had been arrested while another, Mohamed Kadhafi was interviewed by Al-Jazeera television cowering in his house, afraid to leave.
The International Criminal Court is seeking the transfer of Seif al-Islam to The Hague to face charges of crimes against humanity, the court's spokesman said Monday.
Kadhafi broadcast three defiant audio messages on Sunday, vowing he would not surrender and urging the people of Tripoli to "purge the capital, even as rebel forces swept through the capital and took over the symbolic Green Square at the waterfront. But he has not been seen in public for weeks.
Kadhafi's Bab al-Aziziya compound has been blasted regularly since the start of the international military intervention in Libya on 19 March and most of the buildings in the complex have been flattened. But Kadhafi has many bunkers there where he could take cover in.
EU foreign affairs chief Catherine Ashton says the end of the Kadhafi regime in Libya is near and called on Kadhafi to relinquish all power to avoid further bloodshed.
The spokesman for the European Union's High Representative for Foreign Affairs also urged the rebel forces to "fully respect humanitarian and human rights law and protect citizens," as they gain control of the country.
"It is critical that the authorities work to honour the aspirations expressed by the revolution for the establishement of a democratic, just and prosperous Libya," he added.