Officials of the National Transitional Council, Libya's interim ruling body, said there were only small pockets of resistance in Sabha, the country's largest desert city and home to a strategically vital military base.
The United States prepared, meanwhile, to raise the US flag over its reopening embassy in Tripoli, after President Barack Obama met Libya's new leader in New York and said the world would stand with his country as it consolidates freedom.
"We are in complete control of the city of Sabha. Everybody, including (those who were) pro-Gaddafi, are now with the revolution," said Abdelmajid Seif Ennasr, who represents the NTC in Sabha. The NTC's fighters were only encountering "resistance from some individuals here and there," he told AFP.
"Sabha is totally under the control of the revolutionaries," said Mohammed Wardugu, the Benghazi spokesman of the "Desert Shield Brigade" that is fighting in the region.
The battle for Sabha, a city of 100,000 inhabitants in an area dominated by the Gaddafi clan, first broke out on June 12 after two days of anti-regime protests in the sprawling oasis.
Yesterday Wardugu said the NTC forces had taken control of the airport and a garrison in Sabha and forced 300 Gaddafi mercenaries to flee before capturing 150 of his loyalist fighters.