Rebel fighters have clashed with Libyan government forces near the Tunisian border and in the western town of Zawiyah, threatening a vital supply route to the Libyan capital, Tripoli.
Reporters heard gunfire and skirmishing in the coastal town of Zawiyah, about 50 kilometres west of Tripoli, and the highway from the capital to the Tunisian border is blocked.
Commentators say control of the road could determine the outcome of the Libyan conflict.
Rebels trying to overthrow Libyan leader Muammar Gaddafi hope to capture Zawiyah, an oil refinery town, and cut off his stronghold in the capital from access to the outside world by severing the coastal highway, a lifeline for the embattled government.
They advanced north to within 25km of Zawiyah early on Saturday, after what they said was a six-hour battle which pushed the front line closer to Tripoli, and later said they had fought their way into the centre of Zawiyah.
The government confirmed fighting in the area but said a rebel attempt to capture the city had been beaten back.
