They control most of Zawiya and fighters claim a victory in march on capital, as a key Qaddafi minister seemingly defects.
Rebels say they are just 50km from Tripoli
ZAWIYA, Libya //Rebels said yesterday they had seized most of Zawiya, the final hurdle on the road to Tripoli, as the UN chief's special envoy visited Tunis for talks on Libya's future.
"Basically most of the town is under the control of rebel fighters," the rebel field commander Abdul Hamid Ismail said.
The rebels claimed to have overrun the towns of Sorman, 60 kilometres west of Tripoli and Garyan, 50km to the south as they pushed an assault on three fronts.
Nassr Al Mabrouk Abdullah, the Libyan interior minister, also appeared to have defected as he flew into Cairo on his private plane with nine family members. He came from Tunisia and entered on a tourist visa in what could be a high-level defection.
"We had no idea of his arrival, but he was in Tunisia on Sunday," said a Libyan embassy official in Cairo.
The claimed rebel advances, which would put opposition forces in sight of Tripoli, came as Col Qaddafi railed against the rebels and Nato, amid new rumours that he had been preparing to flee the country.
They also came as UN Secretary General Ban Ki-moon's envoy, Abdul Ilah Al Khatib, flew to Tunis, saying he would join talks between rebels and the Qaddafi regime.
The Jordanian former foreign minister said negotiations on Libya's future would take place in a hotel in the Tunis suburbs.
Mr Khatib has spent months shuttling between Tripoli and the rebel base at Benghazi trying to start ceasefire talks between the regime and the rebels' National Transitional Council.
Sources close to Tunisian security services said representatives of the two warring sides had met in Djerba, near the Tunisian-Libyan border. Negotiations were under way with "several other foreign parties", the national TAP news agency said, without giving details of the content of the talks.
Overnight, Col Qaddafi predicted a swift end for "the rats" and the "coloniser" - the rebels and Nato - in an audio message on Libyan television, extracts of which were published by official news agency JANA.
"The coloniser and its agents can now only resort to lies and psychological warfare after all the wars with all the weapons have failed," Col Qaddafi said. He called on his supporters to "prepare for the battle to liberate" rebel-held towns.
Rebels had on Saturday entered Zawiya, making swift advances, but became bogged down on Sunday when they suffered heavy casualties amid shelling.
Mr Ismail, the rebel commander, said battles for Zawiya had raged through the night on Sunday into yesterday, with five rebels killed, and that Col Qaddafi's forces had been pushed to the eastern outskirts. By the afternoon the fighting had died down. Rebels also battled loyalist forces around oil installations in Brega yesterday.
Rows of seaside apartment blocks that once housed the workforce in Brega were under total rebel control. The government spokesman Mussa Ibrahim, meanwhile, said the regime's armed forces were capable of retaking rebel-held towns and districts. "Our mujahideen forces are capable of exterminating these gangs," he told a news conference in Tripoli.
Mr Ibrahim acknowledged problems in Sorman, 60km west of Tripoli, but "hundreds of volunteers" backed by the army were "handling the case", he said.
He said that the rebels had entered Garyan in the Nefusa mountains "to spread terror ... but there is no need for concern" since government troops would retake the town "in the next few hours".
Abdulsalam Othman, the spokesman for the rebels' western military council, said yesterday that both Garyan and Sorman were in rebel hands, as was the short stretch of road linking Sorman to Zawiya.
He said the advances meant that Tripoli's supply lines from Tunisia had been severed.
The advance on Sorman started at dawn on Sunday, Mr Othman said.
After more than 10 hours of intense battle, the rebels managed to force Col Qaddafi's troops to retreat. During the fight, more than 40 fighters, some of them sub-Saharan African mercenaries, were captured.
South of the rebel town of Misurata, 200km east of the capital, the rebels had consolidated their positions in Tuarga after taking control of it on Friday and said they faced only some pockets of resistance.
But Mr Ibrahim said pro-Qaddafi forces had "retaken control of the town and killed most of those from the Misurata-based gangs who advanced on Tuarga". Neither claim could be independently verified.
* Agence France-Presse with additional reporting by Associated Press