The former leader's whereabouts are unknown, but his spokesman said Gadhafi is still in Libya.
Rebels said they have captured the eastern town of Bin Jawwad from loyalists and are threatening to advance on Gadhafi's hometown of Sirte.
The rebels now control most of Libya but are struggling to alleviate shortages of water, fuel and electricity in Tripoli.
Also Sunday, some 50 charred bodies were discovered in a makeshift lockup near a military base that had been run by one of Gadhafi's sons.
New York-based Human Rights Watch said the evidence it has collected so far "strongly suggests that Gadhafi government forces went on a spate of arbitrary killing as Tripoli was falling." The justice minister in the rebels' interim government, Mohammed al-Alagi, said the allegations would be investigated and leaders of Gadhafi's military units put on trial.
The Associated Press contributed to this report.