A captured general loyal to Libyan strongman Muamar Qaddafi says the regime has maintained key tribal support in a belt around the capital.
In addition, Khaled Kaim, the deputy foreign minister, revealed Saturday that the rebels failed to take the gateway city of Bani Walid in eastern Libya.
"The rebels are now under severe pressure from France, Britain and Qatar to get the job done," he said. "They are being told that you do it or you lose our support. NATO is urging Libyans to kill fellow Libyans.
"But when they tried to take Bani Walid, after Nato bombed the checkpoints, the Bani Walid tribe came out and pushed them back."
Loyalist claims that much of Libya remains faithful to Qaddafi have been panned by Western officials as reports of dissension in the ranks over his decision to make alliances with Islamic extermist groups comes to light. Libya had long been considered a 'moderate' Arab state.
But Brigadier-General Hadi al-Ujaili, a member of Libya's intelligence service captured by the rebels, rejected the idea that Tripoli would eventually fall.
"For the most part Tripoli is stable. There is some opposition to Qaddafi, but I would say he is safe," said Brig Ujali, who was captured by rebels who are encroaching on Zawiyah, a key town 30 miles west of Tripoli.
"Qaddafi still has the support of key tribes. He is still very strong. He is under threat, but pushing him out will be very difficult. The tribes are the key. He has their support."
Rebel commanders in western Libya captured the front line towns of Bir Ghanam and Nasir and have set their sights on Zawiyah
, which sits on the main road between the capital and the Tunisia border.
By cutting off the road through Zawiyah, the rebels would sever Qaddafi's main lifeline to bring in fuel, food and other necessities. Brig Ujaili, however, warned the rebels would face tough resistance from heavily armed Gaddafi troops.
"Qaddafi has more than 1,000 men there. They are mostly conscripts. Since the rebels have been moving, he has been building up his people there," he said.