Tunis: Rebels battled for towns on either side of the Libyan capital Tripoli on Saturday, and fighting spilled across the border into Tunisia where Libyan infiltrators clashed with Tunisian troops.
The United States said Muammar Gaddafi`s "days are numbered" as insurgents, backed by NATO air strikes, put his four-decade rule in the North African nation under unprecedented pressure amid reports of more defections from his ranks.
Tunisian security sources said their forces had intercepted Libyan men in vehicles with weapons and fought them through the night in the desert. They reported several casualties.
The six-month-old war in Libya came close to the frontier this week after rebels suddenly seized the coastal city of Zawiyah just 50 km (30 miles) west of Tripoli, surrounding the capital and severing its supply routes.
Intense fighting continued in Zawiyah on Saturday and rebels occupying the centre of the city said pro-Gaddafi forces showed no sign of retreating to the capital.
Gaddafi soldiers west of Zawiyah and near the Tunisian border have been effectively encircled and cut off from their supply lines, and Tunisia has beefed up its military presence in the border area.
Residents of the southern Tunisian desert town of Douz said by telephone that helicopters were swooping overhead and troops had been summoned from nearby towns to subdue the infiltrators, who rode in vehicles without number plates.
The Tunisian security sources did not say whether the armed men were rebels or supporters of Gaddafi, but residents said they believed they were Gaddafi supporters.
Tunisian officials also said a Tunisian Army helicopter had crashed because of mechanical problems in the border area, killing the pilot and co-pilot.