Muammar Gaddafi's fighters fired several mortars and tried to ambush revolutionary forces today at the northern gate of the loyalist stronghold of Bani Walid.
With their numbers stretched thin, the former rebels sent reinforcements, some arriving with a tank seized from the ousted regime.
Libya's new rulers, meanwhile, pressed forward with efforts to assert authority over the country. The National Transitional Council planned a press conference later today to announce a new Cabinet line-up.
The two sides have clashed for days after former rebels pushed towards Bani Walid and Gaddafi's home town of Sirte to try to crush the dug-in fighters loyal to the fugitive leader.
While Sirte would be a major symbolic prize, Bani Walid has proved particularly difficult for revolutionary forces.
The loyalists hold the strategic high ground along the ridges overlooking a desert valley called Wadi Zeitoun that divides the town between northern and southern sections.
Today, Gaddafi's forces blasted fighters at the northern entrance with mortar fire while the revolutionary forces returned fire with machine guns and rocket-propelled grenades.
Fighters also fired into the desert north of the gate where Gaddafi loyalists were believed to be trying to surround them ahead of an ambush.
Five mortar shells landed about 20 yards from a building where anti-Gaddafi fighters were resting, prompting them to run to a feed factory they have occupied.
The reinforcements from Tajoura posed on a tank they said was captured after revolutionary forces swept into Tripoli on August 21. Fathi Mselati, 31, from the Tajoura brigade, said more captured tanks were on their way to the front.
Revolutionary forces also faced fierce resistance in Sirte as they tried to push through crowded residential areas in the coastal city.
The forces were met by gunfire, rockets and mortars. A field hospital was set up outside Sirte at a gas station filled with wounded fighters, including some from a convoy hit by a rocket-propelled grenade. Twenty-four anti-Gaddafi fighters were killed and 54 wounded in the day's battles, the military council from the nearby city of Misrata reported.
The pro-regime radio station in Sirte repeatedly aired a recorded message it said was from Gaddafi, urging the city's defenders to fight on.
The voice resembled Gaddafi's but its authenticity could not be confirmed.
Gaddafi's spokesman, Moussa Ibrahim, vowed: "We have the ability to continue this resistance for months" in a phone call on Friday to Syrian-based Al-Rai TV.
Hassan Dourai, Sirte representative in the new, interim government, said fighters reported seeing one of Gaddafi's sons, Muatassim, shortly before the offensives began on Friday, but he has not been spotted since the battles intensified. The whereabouts of Gaddafi and several of his sons remain unknown.
On a third front in Libya's southern desert, hundreds of revolutionary fighters were negotiating with villagers in the still pro-Gaddafi region to surrender peacefully. The fighters collected on a road near the Nahrouqa village today.
Col Bashir Awidat has said they seek to secure the surrounding hinterlands before moving against Sabha, the main southern urban centre about 400 miles south of Tripoli.