|Al Jazeera's Jacky Rowland reports from Ras Lanuf where rebels have successfully resisted a government attack
Opposition forces in Libya are bracing for a prolonged campaign in their bid to overthrow the regime of Muammar Gaddafi, the country's long-time leader, as their fighters battle to repulse ferocious assaults by government soldiers.
Forces loyal to Gaddafi advanced on the rebel-held oil port of Ras Lanuf on Monday in a counter-attack that forced residents to flee and rebels to retreat.
The Libyan army was moving down the strategic Mediterranean coastal road east of the recaptured town of Bin Jawad, heading towards Ras Lanuf which is about 60 km away and which has a major oil complex, witnesses told Reuters news agency.
Dozens have died in a dramatic escalation of the conflict gripping the oil-rich North African nation, as anti-government forces' saw their rapid advance to the capital Tripoli abruptly halted.
|This battle map shows areas under rebel control
"For a few days the rebels were making gains, but overnight it would appear that pro-Gaddafi forces took some ground," Al Jazeera's Jacky Rowland, reporting from Brega, said on Monday morning.
Government forces appeared to have "drawn a line in the sand" on the road to Sirte, Gaddafi's hometown, she added. "If the rebels want to capture Sirte, they will have to prepare for heavy fighting along the way."
At the hospital in Brega, 42 injured members of the opposition force were being treated, while there were confirmed deaths of at least eight, our correspondent reported.
"The vast majority of those injured had been injured by their own weapons," she said, explaining that the rebels had little or no military training.
Meanwhile in Az Zawiyah, witnesses reported that the city was under heavy attack by government troops.
Lutif al Zawee, a journalist from the western city, told Al Jazeera that the city was under heavy attack from various directions. He said that heavy smoke was coming up from the city centre and a mosque had been hit as well.
In the rebel stronghold of Benghazi, much of the euphoria and excitement that victory was close at hand had faded, said Al Jazeera's Hoda Abdel-Hamid.
Some feared that pro-Gaddafi forces had deliberately retreated to around Sirte, drawing the inexperienced and poorly-equipped rebel fighters forward and leaving rebel-held towns exposed to a possible counter-offensive.
"Some people told me all the young people had gone to the front. There is no one left to protect the city," said Abdel-Hamid. "There is an understanding that [Gaddafi's ousting] is not going to happen so easily."
Gaddafi has faced a popular uprising demanding democracy and an end to his nearly 42-year rule since February 17.
With helicopter gunships, fighter planes and tanks, Gaddafi loyalists have pounded opposition fighters with artillery, rockets and gunfire in several cities, including Bin Jawad, Tobruk, Ras Lanuf and Misurata.
Bin Jawad, previously held by rebels, was reclaimed by government forces on Sunday, but opposition fighters continued to advance on the area amid conflicting claims about the capture and recapture of several strategic Libyan cities and towns.
Mohammed Ali, a rebel leader and a member of the civil committee for Misurata affairs, told Al Jazeera that opposition forces are in "firm control" of Misurata.
"We have also captured Gaddafi soldiers, and we will interrogate them. They will be shown on TV," he said.
But Ali said that his fighters are outgunned and appealed for aerial support.
"We ask the international community for specific surgical attacks on Gaddafi's air force capabilities," he said, adding that a no-fly zone "is long overdue."
Sources report deadly clashes took place in the area that lies in the middle of the coastline between the opposition stronghold of Benghazi and the capital, Tripoli, over which Gaddafi retains a tight grip.
Injured opposition fighters had been taken to the local hospital in nearby Ras Lanuf, a rebel-held town.
Abu Sadr, an opposition activist in Benghazi, told Al Jazeera that for the time being people in the city were very relaxed.
"We know we are safe from any attack on the ground and government forces are not going to come into Benghazi unless it is an airforce attack," Sadr said.
"From Brega to Ras Lanuf is important, because Gaddafi forces are very close."
Rebels in Misurata also beat back Gaddafi's forces in heavy fighting that left 18 people killed, a local doctor told the Reuters news agency.
Gaddafi TV appearance
Gaddafi, meanwhile, made a fleeting appearance on Libyan state television on Sunday night, but disappeared almost immediately.
Crowds were seen celebrating and shouting the leader's name as he appeared in Tripoli's Green Square, but no explanation was given as to why state TV did not stay with footage of the president. They instead cut back to the studio, going on to a separate interview.
Al Jazeera's Charles Stratford reports on the recent fighting across the country.
This comes after heavy shooting was heard in Tripoli early on Sunday. The government said there was no violence in the capital, and called the shots "celebratory fireworks".
Mussa Ibrahim, the Libyan government spokesman told the Reuters news agency: "Everything is safe. Tripoli is 100 per cent under control. What you are hearing is celebratory fireworks. People are in the streets, dancing in the square."
It was unclear who was carrying out the shooting, or what caused it, Al Jazeera's Anita McNaught reported from the city.
Automatic weapon rounds, some of it heavy calibre, echoed around central Tripoli along with pro-government chants, whistling and a cacophony of car horns as vehicles sped through the vicinity, witnesses said.
"I assure you, I assure you, I assure you, I assure you, there is no fighting going on in Tripoli," Ibrahim said
Our correspondent, reporting from Green Square, said that thousands of people had turned out to show their support for Gaddafi.
“The square is absolutely packed with supporters of Gaddafi," she said, adding that some of these "supporters" had admitted to a British journalist on Sunday that they were army and police personnel in civilian clothes.
Against this backdrop of continued fighting, the UN Security Council will name Portugal to head its Libya sanctions committee, Al Jazeera has learnt.
Guido Westerwelle, the German foreign minister, became the latest political figure to call for fresh sanctions against Gaddafi.
|Read more of our Libya coverage
Meanwhile, the European Union has sent experts into Libya to get "real time" information on humanitarian and evacuation efforts there
"I have decided to dispatch this high level mission to provide me with first-hand, real-time information to feed into the discussions leading up to Friday's extraordinary European Council when I will update heads of state and government on the situation," Catherine Ashton, EU foreign minister, said on Sunday.
On the other side of the Atlantic, John Kerry, the chairman of the US Senate Foreign Relations Committee, said once again that the US and its allies should plan for a no-fly zone over Libya.
His remarks come just days after Robert Gates, the US defence secretary, said that a no-fly zone was tantamount to going to war because it would call for attacking Libya's air defences.