|Al Jazeera's Zeina Khodr reports that rebels now control most of the strategically important city of Az-Zawiyah
Libyan opposition forces have pushed further to isolate Tripoli, moving towards a western town that links the capital and Sirte - the hometown and a stronghold for the Libyan leader, Muammar Gaddafi.
"The scouting teams of the revolutionaries reached the outskirts of Al-Heisha after expelling Gaddafi forces," the rebel military command said in a statement early on Wednesday.
Al-Heisha lies roughly 70km south of Misrata and 250km from Tripoli, near two key crossroads that link loyalist-held territory in the west with that in the oil-rich Sirte basin.
It was just the latest in a series of battlefield operations to isolate the capital.
In addition to gaining a foothold in Az-Zawiyah, rebels said they had taken two towns near Tripoli on key supply roads Gharyan, 80km south of the capital and Surman, less than 16km west of Az-Zawiyah.
"Gharyan is fully in the hands of the revolutionaries," a rebel spokesman, Abdulrahman, said by telephone. "Gaddafi has been isolated. He has been cut off from the outside world."
Government spokesman Moussa Ibrahim acknowledged in remarks broadcast on state television that rebel fighters were in Gharyan. "There are still armed gangs inside the city. We are able to drive them out," he said.
But while rebels controlled most of Az-Zawiyah, Gaddafi forces shelled the city, wounding several civilians.
Funerals were held for 23 others who rebels said were killed the previous day.
Nuri el-Bouaisi, an oil production engineer in the city, said rebels had cut off pipelines that transport gasoline and diesel fuel to Tripoli.
"We shut down all four pipelines to Tripoli," El-Bouaisi said, whose claim could not be verified.
NTC-Gaddafi talks denied
Meanwhile, a UN envoy has arrived in neighbouring Tunisia, where sources say rebels and representatives of the government are in talks on the island resort of Djerba.
The envoy, Abdul Ilah al-Khatib, told the Reuters news agency he would meet "Libyan personalities residing in Tunisia" to discuss the conflict.
Talks could signal the endgame of a battle that has drawn in NATO and emerged as one of the deadliest confrontations in the wave of unrest sweeping the Arab world.
But UN spokesman Farhan Haq said the world body had "no concrete information" on any talks in Tunisia and that its Libya envoy, al-Khatib, was not taking part in any such talks.
|Weitz told Al Jazeera use of scuds may not be an escalation of the war but they do send a message
The reports of rebel-government talks also sparked a swift denial from Gaddafi's government. His spokesman dismissed reports of negotiations about the Libyan leader's future as part of a "media war" against him.
"The leader is here in Libya, fighting for the freedom of our nation. He will not leave Libya," spokesman Moussa Ibrahim said.
Abdul Hafez Ghoga, vice-chairman of the National Transitional Council (NTC), also denied that such talks were under way.
Gaddafi forces on Sunday fired a scud missile near Brega on the main frontline in the east of the country - the first use of the weapon since the uprising against his rule began six months ago, according to a US military official.
Although no one was hurt in the attack and the missiles are considered unreliable weapons, Richard Weitz, director of the Centre for Political and Military Analysis at the Hudson Institute, told Al Jazeera the use of scuds could signal Gaddafi's determination to fight.