Libyan leader Muammar Gaddafi has urged his supporters to fight for the country "inch by inch" as opposition forces launched a two-pronged offensive in western Libya that threatens to isolate the capital of Tripoli.
Facing the sternest challenge of his decades-long rule, Gaddafi on Monday called on Libyans to arm themselves to liberate the country from "traitors and from NATO" in a broadcast on state television.
The speech, which was broadcast in audio only with no images, was the first time Gaddafi had spoken in public since rebel fighters launched their biggest offensive in months.
"The Libyan people will remain and the Fateh revolution [which brought Gaddafi to power in 1969] will remain. Move forward, challenge, pick up your weapons, go to the fight for liberating Libya inch by inch from the traitors and from NATO," Gaddafi said.
"Get ready for the fight ... The blood of martyrs is fuel for the battlefield," he added.
Meanwhile, Egyptian airport officials say the Libyan interior minister has arrived in Cairo with family members.
The officials say the minister, Nassr al-Mabrouk Abdullah, landed just before noon on Monday at the Cairo international airport, with nine members of his family.
They say he arrived on a special plane from Tunisia and told Egyptian officials that he was "on a tourist visit''.
The airport officials spoke on condition of anonymity because they are not authorised to talk to the media.
Reports have been circulating for hours that the minister had defected from the side of Gaddafi, who is facing a possible breakthrough in a six-month-old rebel campaign to end his four decades in power.
No officials from the Libyan embassy in Cairo were at the airport to greet the minister. Libyan officials were not immediately available for comment.
Opposition fighters fought for control of the towns of Gharyan and Az-Zawiyah on Sunday, attempting to cut off the southern coastal route from Tunisia that Gaddafi uses for supplies.
Zeina Khodr, Al Jazeera's correspondent in Az-Zawiyah, reported that the rebels had taken control of a bridge along which the highway from Tripoli to Tunisia runs, but that central areas of the city remained contested, with Gaddafi forces employing snipers and mortar fire.
The battle also raged near the gates of the city.
Al Jazeera's Khodr said opposition fighters claimed to have taken 70 per cent of the town, despite the threat of snipers.
Bashir Ahmed Ali, the rebels' battalion commander in Az-Zawiyah, said that his forces had suffered "many casualties" due to sniper fire. He also told the AFP news agency that a tank and four fighters had been lost in a "friendly fire" air strike during the operation to take Az-Zawiyah.
The gains were possible "because the Gaddafi forces' defences were weak and fighters received help from inside the city. As they expected, residents took up arms and fought alongside them when they arrived," Khodr reported.
"The town had previously risen up against Gaddafi, but government forces quelled that uprising.
"Today's victory would be the opposition's most significant in months because they were just 50km from Tripoli, a mere half an hour's drive, if they could hold the territory and stave off a Gaddafi counter offensive," our correspondent said.
Libyan government spokesman Moussa Ibrahim rejected the claims: "Az-Zawiyah is completely under our control. A very small group of rebels tried to enter from the south of Az-Zawiyah but they were stopped easily by our armed forces."
Early on Sunday, rebel fighters claimed victory in Gharyan after Gaddafi's soldiers withdrew. Government forces returned several hours later, however, and clashes restarted.
The rebels also claimed to have taken control of the western town of Surman.
Rebel forces launched ground attacks after NATO planes hit targets in these areas.
Clashes were also reported in the eastern oil town of Brega, where the rebels say they now control two-thirds of the town.
Al Jazeera's Tony Birtley, reporting from Brega on Monday, said that the town showed signs of intensive fighting having taken place, and that the rebels were continuing a push to take the oil terminal and industrial area.
The government denied on Sunday that rebel forces controlled any part of Brega.
Opposition forces hope that by taking complete control of the city, its oil terminal and sea port will allow them to resume oil exports, and will give them a key staging area on the road to Sirte, a Gaddafi stronghold.
Capture of Tawurgha
|Despite battlefield gains, the Libyan rebels still face the threat of internal divisions [Al Jazeera]
On the western front, opposition commanders said they had control of the town of Tawurgha on Sunday, as they pushed to cut supply routes to forces loyal to Gaddafi.
In a symbolic show of victory, fighters tore down green flags that had been hoisted atop buildings by Gaddafi supporters who had occupied the area.
"Gaddafi is finished!" shouted a jubilant fighter.
The rebels encountered heavy fighting and sizable pockets of resistance among a maze of buildings and date palms.
Al Jazeera's Andrew Simmons, reporting from Tawurgha, said it was a heavily co-ordinated operation with NATO, with six tanks involved.