|Al Jazeera's Zeina Khodr reports that rebels now control most of the strategically important city of Az-Zawiyah
Libyan leader Muammar Gaddafi's forces fired a scud missile for the first time since the uprising against his rule began six months ago, but it landed in the desert and injured no one, a US military official said.
The missile was fired on Sunday morning from a location about 80 km east of Sirte, Gaddafi's home town, and landed east of the coastal oil-rich town of Brega, the official said late on Monday.
Brega has been the main frontline in the east of the country for months. Rebels have seized the port's eastern residential areas since last week, but Gaddafi's forces still control its oil terminal, refinery and port.
The use of scud missiles by Gaddafi could harm civilians, but has as much chance of changing the military course of the war as "throwing dishes against a wall", Colonel Roland Lavoie, a NATO military spokesperson said on Tuesday.
Richard Weitz, director of the Centre for Political and Military Analysis at the Hudson Institute, told Al Jazeera the use of scuds may not be an escalation of the war but they do send a message.
"This is more of a political signalling on Gaddafi’s part, in that he's been making a series of threats in the past and so far those have been discounted; however, by escalating to the use of missiles it shows his determination to fight," he said.
'Any weapon necessary'
In the rebel-held town of Benghazi, a rebel army spokesman said it was no surprise that Gaddafi was making use of his ageing stockpile of Soviet-era scud missiles, which have an estimated range of about 300 km.
|Weitz told Al Jazeera use of scuds may not be an escalation of the war but they do send a message
"The tyrant's [Gaddafi] regime possesses such missiles and they are able to use them. This man will use any weapon necessary to keep his regime going and resume his rule, even for a few hours. We are used to facing such unpredictable and crude behaviour from those who have lost legitimacy and credibility," Ahmed Bani said.
US military officials said it was unclear what Gaddafi might have been targeting.
However, the attack came in the wake of recent rebel gains that have increased pressure on the Libyan leader.
Libyan rebels said on Monday they had seized a second strategic town near Tripoli within 24 hours, completing the encirclement of the capital in the boldest advances yet of their uprising against Gaddafi.
US officials said they believed Libyan rebel advances were choking off Gaddafi's forces in the capital, Tripoli, and significantly increasing pressure on him.
Gaddafi's forces have been weakened and his "days appear to be numbered", Leon Panetta, the US Defense Secretary said.
Gaddafi's forces fired mortars and rockets at the coastal town of Az-Zawiyah a day after rebels captured its centre in a thrust that severed the vital coastal highway from Tripoli to the Tunisian border, a potential turning point in the war.
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.
In addition to gaining a foothold in Az-Zawiyah, rebels said they had taken two towns near Tripoli on key supply roads Gharyan, 80 km south of the capital and Surman, less than 16 km 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.
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.
"Gaddafi is fighting for the freedom of our nation ... He will not leave Libya"
Libyan government spokesman
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 the NATO alliance and emerged as one of the deadliest confrontations in the wave of unrest sweeping the Arab world.
But spokesman Farhan Haq said the United Nations had "no concrete information" on any talks in Tunisia and that its Libya envoy, al-Khatib, was not taking part in any such talks.
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.