The rebels replied with anti-tank fire Forces loyal to Libyan leader Muammar Gaddafi launched a counterattack on Sunday against rebel advance positions 50 kilometres (30 miles) southwest of Tripoli, an AFP correspondent reported .
Loyalist forces fired half a dozen Grad rockets into the hamlet of Gualish.
The rebels replied with anti-tank fire as they sought to maintain their grip on Gualish, a key gateway on the road to the capital Tripoli that they seized on Wednesday.
Just hours before the government attack, NATO warplanes bombed positions in the area, the correspondent said. A colonel in the rebel forces said the raid struck near Asablah, 17 kilometres from Gualish.
In its daily update, the Western military alliance said its planes carried out 48 strike sorties on Saturday, with the focus on Misrata.
Meanwhile, rebel troops advancing into the loyalist stronghold of Zliten said Sunday they lost one fighter and had 32 wounded by landmines laid by Gaddafi\'s retreating troops.
Insurgents pressing out westward from the long-besieged city of Misrata said the ordnance was laid by Gaddafi loyalists falling back from their positions around Zliten.
Zliten, once considered a bastion of Gaddafi forces, is a key link on the road from rebel-held Misrata to Tripoli.
Libyan rebels said they were preparing on Saturday to push forward in their drive on Tripoli from both the south and west in a bid to isolate Kadhafi in his ever-closer capital.
But the embattled leader remained defiant, telling supporters on Friday that \"the regime in Libya will not fall.\"
After heavy fighting, rebel fighters captured the desert hamlet of Gualish on Wednesday, taking them closer to the strategic garrison town Gharyan and the last major objective standing between them and Tripoli to the north.
For now, they have set their sights on Asablah, on the road to Gharyan, 80 kilometres from Tripoli.
A second target in a three-pronged strategy is the coastal city of Zawiyah, one of the last major loyalist strongholds west of Tripoli.
And from a base in Misrata, 215 kilometres east of the capital, the rebels reported on Friday battling to within two kilometres of the centre of Zliten town with the loss of five dead and 17 wounded.
\"When we take Zliten, enforced with Misrata, it gives us a clear path\" to Tripoli, rebel spokesman Colonel Ahmed Omar Bani said.