Fierce fighting raged on Monday in Bani Walid as new Libyan regime fighters attacked the oasis town where Moamer Kadhafi's son Seif al-Islam is believed holed up, possibly with his father.
"The revolutionaries came to Bani Walid this morning and engaged in a hard battle," said Abdullah Kenshil, a senior official in the National Transitional Council (NTC).
Kenshil said the battle against Kadhafi's mercenaries for control of Bani Walid, one of the ousted strongman's few remaining bastions southeast of Tripoli, was a "done deal and will be completed in the next two days."
He said Seif al-Islam had been seen in Bani Walid, and that Kadhafi himself was also likely to be there.
"Seif al-Islam was seen in Bani Walid; this is 100 percent certain. As for his father, he was there too; we are 70 percent sure," Kenshil told AFP, adding they were being defended only by mercenaries.
"Those fighting in Bani Walid are not necessarily Kadhafi's brigades, whose members joined the NTC forces," said Kenshil. He said bodies recovered indicated the mercenaries were from Chad, Niger and Togo.
Kadhafi, Seif al-Islam and intelligence chief Abdullah al-Senussi have been on the run since rebels overran Tripoli on August 23. They are wanted by the International Criminal Court for alleged crimes against humanity.
Frustrated fighters, meanwhile, complained that a lack of organisation and coordination was delaying Bani Walid's capture.
"Some people are angry. A week ago we said we would liberate Bani Walid within hours but it is a difficult front line, the resistance is tough and worse, there is no coordination between the revolutionaries," said one, Abdu.
Mustafa bin Dardaf, a commander with the Zintan Brigade, told AFP that one of his fighters was killed on Monday and another wounded in the battle for Kadhafi's hometown Sirte on the Mediterranean coast.
NTC fighters said a field hospital five kilometres (three miles) from Sirte city centre was targeted by rockets, forcing doctors to flee and evacuate patients.
Four rockets hit outside the field hospital but no one was hurt, they said.
An AFP correspondent east of Sirte said retreating Kadhafi forces laid down an intense and steady bombardment as they pulled back.
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Pro-NTC forces resumed the battle for Sirte after regrouping overnight.
Dozens of families on Monday fled Sirte as explosions rocked the city.
"Things are not good because of the clashes," said Tarek Mohammed, fleeing the city with his wife and daughter.
One family heading for Misrata charged that forces loyal to Kadhafi used them as "human shields" by deploying their guns inside residential areas and preventing them from leaving.
NATO warplanes also struck on Monday as NTC forces focused on the Ouagadougou conference centre in Sirte, where Kadhafi used to hold Pan-African symposiums, a spokesman for Misrata's military media council said.
NTC fighters suspect the complex is a Kadhafi loyalist command centre and the new base of the infamous 32nd brigade led by Khamis Kadhafi until he was reported killed last month.
Front line fighters in Sirte are convinced that Mutassim Kadhafi, a career soldier and former national security adviser to his father, is hiding in Sirte.
Intercepted radio chatter showed a lieutenant with the codename Abu Bakr ordering Kadhafi loyalists to use heavy artillery despite counter-appeals to protect civilian life, an AFP journalist said.
"Shoot, shoot," crackled the radio. Later the same pro-Kadhafi commander promised to rescue Mutassim, saying: "Master, master... we will protect you as ordered by your father," according to fighters.
The report could not be verified by Misrata's military council.
In Geneva, meanwhile, a UN team set up to investigate rights violations in Libya said it was concerned about allegations that many black Africans were being illegally detained there.
"In recent weeks, reports have emerged of the mass arrest of black Africans who are suspected of being pro-Kadhafi mercenaries," Philippe Kirsch, a member of the International Commission of Inquiry on Libya, told the Human Rights Council.
"It has been reported that large numbers of migrant workers from Chad, Mali, Niger, Nigeria and Sudan have allegedly been arbitrarily arrested by security forces of the NTC in Tripoli," he said.
Meanwhile, Bolivia's President Evo Morales upbraided the UN Security Council for approving NATO military action against Libya, calling the operations "a shame for humanity."
"What Security Council? I would say it is a council of insecurity," Morales said in Monday in Cuba for talks with President Raul Castro on his way to the UN General Assembly.