A witness says 18 people have been killed and 120 wounded in fighting with Libyan leader Moammar Gadhafi's forces that attacked the rebel-held city of Zawiya on Friday.

The witness at Zawiya's hospital said rebels were battling regime troops that attacked on both sides of the city. Zawiya is the closest opposition-held city to Tripoli, Gadhafi's stronghold 50 kilometres to the east.

He and other residents, who spoke on condition of anonymity for fear of future retaliation from security forces, said the city remains in opposition hands.

Fresh battles also broke out on at least two other fronts in the country and government loyalists quelled protests in the capital, Tripoli.

In the rebel stronghold of Benghazi, hospital officials said an explosion at an ammunition depot killed at least 17 people.

Friday's blast at a military base also hit a nearby residential area. Witnesses on the scene, about 32 kilometers from downtown, said ambulances are rushing to the area and secondary explosions caused two fire trucks to blow up.

The cause of the blast is unclear. A doctor said it was triggered when people apparently went into the storage facility to collect weapons, but others blamed pro-Gadhafi forces for triggering the blast.

There were also reports of fresh fighting in Ras Lanuf, an eastern oil port, and Ajdabiya, a city about 160 kilometres south of the rebel stronghold Benghazi.

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Fresh fighting was reported Friday in Zawiya, Ajdabiya and Ras Lanuf. (CBC) ((CBC))

There were also reports of a large force from a brigade led by one of Gadhafi's sons, Khamis, heading the new attack on Zawiya. The troops from the Khamis Brigade reportedly fired mortars and then engaged in battles of heavy machine guns and automatic weapons with armed residents and allied army units.

In Ras Lanuf, Reuters reported the sounds of artillery and explosions, along with claims by rebels that they have taken control of the airport. Al-Jazeera reported that four were killed in fighting there.

Essan Gheriani, an opposition activist in Benghazi, said pro-government helicopters were attacking rebel positions in Ras Lanuf.

"The news that we have is than the rebels were able to put [Ras Lanuf] under control," he told CBC News. "But we also have news now that air strikes are being directed there."  

Reuters later quoted Libya's deputy foreign minister as saying pro-government forces were again in control of Ras Lanuf.

As well, rebel volunteers guarding a munitions base in Ajdabiya told Reuters that a warplane bombed the area but did not hit the base. It was the third straight day of strikes by Libyan warplanes.

The CBC's Carolyn Dunn said from Benghazi on Friday some people in eastern Libya believe the pilots might be missing their targets on purpose.

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Rebel fighters pray during a battle near the oil port of Ras Lanuf on Friday. ((Goran Tomasevi/Reuters))

Dunn said prayers in the rebel stronghold were a highly charged political event with a message sent by an imam telling crowds of men, "It is time to prevail, that Gadhafi must go, that the people are coming for Tripoli. This was a call to arms."

The BBC reported rebels in eastern Libya have said they will not negotiate unless Gadhafi, who has ruled Libya for more than 40 years, quits and goes into exile.

An eyewitness report

Mustafa, a landed immigrant who lives in Edmonton but who was in Libya visiting his family, said Friday that he was driving from Brega to Benghazi and every person he sees is armed. Thousands of people are heading to Tripoli to fight, he said.

"Children have guns," he told CBC News. "There are no rules." Mustafa did not want his full name used for fear of reprisals on his family.

When he was in Brega Wednesday, he said planes could be heard four or five times, followed by explosions not far from where he was.

"Everyone says we are going to fight until we die," he said. "A lot of people say things that make me very nervous. I can see in the people, everyone wants to fight."

Gadhafi has resisted calls for change and has vowed to fight to the end.

The entire east has fallen into the hands of the rebellion, as have several cities in the west close to his bastion in the capital. The rebels — ragtag forces of armed residents backed by some military units — have repelled repeated attacks by pro-Gadhafi forces trying to take back their territory.

In his stronghold, Tripoli, government loyalists fired tear gas at protesters Friday as a fierce crackdown that has terrorized parts of the capital the past week seemingly smothered attempts to revive demonstrations calling for the Libyan leader's ouster.

More than 1,500 protesters marched out of the Murad Agha mosque after noontime prayers in the eastern Tripoli district of Tajoura, chanting "the people want to bring the regime down" and waving the red, black and green flag of Libya's pre-Gadhafi monarchy, which has been adopted as the banner of the uprising.

But pro-Gadhafi forces quickly moved in. They fired volleys of tear gas and — when the marchers continued — opened fire with live ammunition, according to witnesses.

It was not clear if they fired at the crowd or into the air, but the protesters scattered, many of them taking refuge back in the mosque, according to an Associated Press reporter at the scene. A doctor said several people were wounded and taken to a nearby hospital.

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Protesters attend an anti-Gadhafi demonstration in Benghazi on Friday. (Suhaib Salem/Reuters)

Before the marches, pro-Gadhafi forces set up checkpoints in the neighbourhood and the country's internet appeared to be shut down. Last week, similar protests were met by a brutal crackdown, when militiamen opened fire on demonstrators moments after they began their marches.   

Libyan authorities barred many foreign journalists from leaving their hotel in Tripoli, claiming it was for their own protection because they had information that "al-Qaeda elements" were planning to open fire on police to spark clashes.

The clampdown underscored the strong hold Gadhafi has maintained over Tripoli, in stark contrast to his dwindling strength in other parts of the country.

Flow of refugees slows

The United Nations humanitarian office estimates that more than 180,000 people have fled the growing unrest in Libya so far.

UN refugee agency spokeswoman Melissa Fleming said Friday the number of refugees crossing into Tunisia had plummeted because Gadhafi supporters had been deployed to the border and are stepping up threats and intimidation of foreign workers trying to flee.

Fleming said less than 2,000 people made it across the border into Tunisia over the last day, compared to 10,000 to 15,000 previously.

Many of those labourers who reached neighbouring Tunisia said they had been robbed by Libyan security forces and ordinary Libyans. They said they were stopped at checkpoints, and were ordered to hand over cash and cellphone memory cards.

An international aid effort is underway at the chaotic Libyan-Tunisian frontier, where about 17,000 people who fled Libya are being housed until they can catch flights to their home countries, said Goran Stojanovski of the UN's refugee agency. More than 200,000 people have fled to Tunisia, Egypt and Niger since Feb. 15, when the uprising against Gadhafi began.

The UN, EU, Britain and Canada have hit Libya and its leadership with a series of economic, travel and arms sanctions and the International Criminal Court said Thursday that Gadhafi and some of his sons will be investigated for alleged crimes against humanity.

The Canadian government on Friday said it welcomed the opening of an investigation by the International Criminal Court. 

"The international community has sent a clear message to the Libyan regime that it cannot act with impunity, and that there will be consequences for committing serious international crimes," said Foreign Affairs Minister Lawrence Cannon, in a statement.

With files from CBC News