By Maria Golovnina and Michael Georgy
TRIPOLI (Reuters) - Muammar Gaddafi's forces battled rebels on several fronts in Libya on Friday and unrest erupted in the capital when gunmen fired to break up crowds shouting "Gaddafi is the enemy of God."
Vowing "victory or death," eastern-based rebels pressed home a westwards push with an attack on the oil town of Ras Lanuf, which lies on a strategic coastal road, claiming to have taken its airport.
In the west, security forces loyal to Gaddafi recaptured parts of Zawiyah, a town near the capital Tripoli that has for days been defying his rule, and residents said at least 30 civilians had been killed, including the town's rebel commander.
News of the fighting pushed up U.S. crude prices to their highest levels since September 2008, and Brent crude futures for April delivery rose $1.36 to $116.17 a barrel.
The International Energy Agency said one million barrels per day (bpd) of Libya's oil output was shut, the top of the range it estimated on Wednesday.
The rebellion in Zawiyah -- the closest rebel-held territory to the capital and the site of another oil refinery -- has been an embarrassment to the authorities who are trying to show they control at least the west of the country.
POPULAR REVOLT
Rebels have already seized control of eastern regions of the country, around the city of Benghazi, the centre of the popular revolt against his four decades of rule.
The uprising against Gaddafi is the bloodiest yet against a long-serving ruler in the Arab world, and the cut in Libya's 1.6 million bpd oil output is a major blow to its oil-dependent economy.
The upheaval has caused a humanitarian emergency on the Tunisian border where tens of thousands of foreign workers have fled to safety. An international airlift is under way, reducing the number of refugees trapped in tented camps.
The rebels earlier told Reuters they were open to talks only about Gaddafi's exile or resignation, following attacks on civilians that have provoked international condemnation, arms and economic sanctions and a war crimes probe.
"Victory or death ... We will not stop until we liberate all this country," Mustafa Abdel Jalil, head of the rebel National Libyan Council told supporters of the two-week-old uprising.
Abdullah al-Mahdi, a rebel spokesman, told Al Jazeera opposition fighters would attack the capital once a "no-fly" zone was enforced by international powers to try to shatter Gaddafi's grip on the country of six million people.
Western nations have called on Gaddafi to go and are considering various options including the imposition of a no-fly zone, but are wary about any offensive military involvement.
In the east, rebels were attacking a military base on the outskirts of Ras Lanuf, an oil port on the Mediterranean, which has a refinery, pipelines and a terminal, and the army responded with artillery fire and helicopters firing machine guns.
Flashes, thuds and bangs resounded from the battlefield, along with wailing sirens and puffs of smoke in the air.
Rebels said they had captured the airport near the town and intended to push forward towards the military base after dark.
An oil facility at Zueitina, south of the Libyan rebel-held city of Benghazi, has been damaged and is on fire, Al Jazeera said, showing a video of black smoke rising from an oil plant.
In Zawiyah, about 50 km (30 miles) west of the capital, pro-Gaddafi forces pushed back an improvised rebel force to the central Martyrs Square, a rebel spokesman said.
A government official said "...maybe there are still some pockets (under rebel control) but otherwise it's been liberated." Talks were under way to persuade the rebels to surrender, he said.
Resident Mohamed said "Dozens were killed and more were wounded .... The hospital was full. They could not find space for the casualties." Resident Ibrahim said 40 to 50 people were killed in the fighting.
Mohamed said the pro-Gaddafi forces had used grenade launchers, heavy machineguns and snipers on the roof of a new hotel to fire at protesters when they marched after Friday prayers to demand the fall of the regime.
In Tripoli, shooting rang out across Tajoura district as Gaddafi loyalists broke up a crowd of protesters seeking an end to his long rule and shouting "Gaddafi is the enemy of God!"
The demonstrators spilt out of the Murat Adha mosque after Friday prayers, and several hundred began chanting for an end to Gaddafi's four decades in power.
"This is the end for Gaddafi. It's over. Forty years of crimes are over," said Faragha Salim, an engineer at the protest in Tajoura.
Up to 100 people in Tripoli had been arrested, accused of helping the rebels, Al Jazeera said.
Earlier on Friday, rebel volunteers said a rocket attack by a government warplane just missed a rebel-held military base which houses an arsenal in the eastern town of Ajdabiyah.
(Additional reporting by Maria Golovnina, Yvonne Bell and Chris Helgren in Tripoli, Tom Pfeiffer and Alexander Dziadosz in Benghazi, Souhail Karam and Marie-Louise Gumuchian in Rabat, Yannis Behrakis and Douglas Hamilton on Tunisia border; Christian Lowe and Hamid Ould Ahmed in Algiers; Writing by Tim Pearce; editing by Myra MacDonald)
