|NTC forces are facing stiff resistance as they seek to wrest control of Bani Walid and Sirte [EPA]
Libya's interim rulers are claiming that their fighters have overrun the key southern city of Sabha, one of the last strongholds of forces loyal to Muammar Gaddafi.
"We are in complete control of the city of Sabha. Everybody, including [those who were] pro-Gaddafi, are now with the revolution," Abdelmajid Seif Ennasr, an official for the National Transitional Council (NTC) in Sabha, told the AFP news agency on Wednesday.
He added that the NTC fighters were only encountering "resistance from some individuals here and there".
"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.
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On Tuesday, Wardugu said the NTC forces had taken control of the airport and a garrison in Sabha and forced 300 pro-Gaddafi mercenaries to flee before capturing 150 of his loyalists.
NTC forces have faced stiffer resistance than expected in their efforts to take Bani Walid and Sirte, two other strongholds of the toppled Libyan leader, and have had several major assaults repulsed by heavy fire from pro-Gaddafi forces.
Many residents of Sabha fear reprisals from the NTC because of a belief that many fought as Gaddafi mercenaries during the civil war.
Sabha, the largest city in the Libyan desert, is home to 100,000 people and an important military base, making it strategically vital.
There were reports earlier that Gaddafi himself may be hiding in the town, along with Saif al-Islam, his most politically prominent son, but NTC fighters in Sabha have reported no signs of them.
Fight for Bani Walid
Meanwhile in Bani Walid, NTC forces moved tanks towards the frontline on Wednesday in an attempt to capture the town.
"Of course it will certainly help us a lot in the final battle. You have seen these tanks. There are also Grads and we will use them by putting them in the front," Abdul Salaam Ganuna, an NTC commander, said.
Almost a month after armed rebels, backed by a NATO bombing campaign, seized control of Tripoli, Libya's new leaders are still trying to assert their authority over the desert town 56km southeast of the capital.
Irregular militias have been pushing into Bani Walid in recent days to confront pro-Gaddafi fighters before pulling back, but forces for Libya's NTC say they are preparing for a co-ordinated military assault in the coming days.
On Tuesday, NTC officials admitted heavy losses in an assault on Gaddafi's hometown of Sirte.
At least three NTC fighters, all in their 30s, were killed and 17 wounded around Sirte as they encountered fierce resistance, said medics.
"The offensive on Sirte has been high intensity in terms of casualties," Dr Suheib Abu Garza told AFP in Misrata, about 150km east of Sirte, where many of the casualties of battle are being brought.
NTC forces suspect Gaddafi enjoys a broad base of support in Sirte.
"The majority of residents are with Gaddafi," said Zuber al-Gadir, a spokesman of the Misrata military council, adding their persistent loyalty to the ousted leader was a legacy of his now defunct propaganda machine.