Published: Aug 19, 2011 5:57 PM EDT

ZAWIYA, Libya (AP) - Libyan rebels took cover from mortars, rockets and anti-aircraft fire Friday as they were pinned down in the center of Zawiya while NATO's bombing campaign helped slow Moammar Gadhafi's ability to send reinforcements to the strategic western city.
    
The fierce onslaught by regime troops in Zawiya, just 30 miles (50 kilometers) west of Tripoli, signaled a slow and bloody push for opposition fighters as they try to advance toward the capital.
    
Still, Gadhafi's troops seemed increasingly isolated, scrambling to use all force available to hold back rebels at the western front. NATO has stepped up bombings in Tripoli in recent days, while rebels blocked Gadhafi's supply route from Tunisia.
    
Fighting in Zawiya has focused on two main streets - Omar Mokhtar and Gamal Abdel-Nasser streets. At the front line, rebel field commander Rida Shaeb said Gadhafi forces held the main Zawiya hospital, as well as a hotel and a bank on the main square. Shaeb's unit of about two dozen men was pinned down about 200 yards (meters) from the main square, and left its position after a particularly heavy barrage of mortars and rockets.
    
Libyan rebels also seized the western city of Zlitan after clashes with regime forces that left 31 rebels dead and 120 injured, a spokesman said. The claim couldn't be independently verified.
    
Government troops have been fighting rebels in the area for months. The town is a major obstacle in the path from the nearby city of Misrata trying to make their way to Tripoli.
    
"The fighters have liberated Zlitan and they are fighting west of the city," said Munir Ramzi of the opposition Misrata Military Council. He said Gadhafi's forces were fleeing after Friday's victory and the rebels are in control of the city.
    
NATO has maintained a bombing campaign on Gadhafi military targets after instituting a no-fly zone decision in March. The coalition said it took out four military facilities and a surface-to-air missile in Tripoli, as well as a command center, two armored vehicles and five tanks on Thursday in Zawiya.
    
The alliance also said NATO warplanes sunk a tugboat carrying troops loyal to Moammar Gadhafi away from Zawiya on Wednesday. The strike occurred after pilots noticed a unit of government troops that had been fighting in the oil refinery using a tugboat "in an attempt to redeploy to new positions," according to British military spokesman Maj. Gen. Nick Pope.
    
One of the jets used a laser-guided bomb to hit the boat, he said in London. "It was clear from their actions that these troops continued to pose a threat to the local population," Pope said. He did not elaborate.
    
An officer at NATO's operational headquarters in Naples, Italy, said a rescue attempt was made after aircraft spotted several survivors of the sinking swimming toward a nearby buoy. The officer could not be identified under standing rules.
    
The NATO bombings, along with the rebels' success in cutting off the supply line to Tripoli with the outside world by controlling the road from the capital to Tunisia, have made it difficult for the Gadhafi regime to reinforce its troops at the front lines.
    
On Gamal Abdel-Nasser Street, rebel fighters took cover behind a building as they were pounded by Grad multiple rocket-launching systems and mortars as well as anti-aircraft missiles.
    
Shaeb's men carried only light weapons and assault rifles; some of his forces also had knives.
    
Zawiya was one of the first cities to rise up against the Gadhafi regime when the Libyan revolt began in mid-February on the heels of the Tunisian and Egyptian revolutions.
    
Protests were quickly crushed by the Gadhafi regime, even going as far as razing a local mosque in the main square that rebels used as a meeting point and makeshift hospital.
    
The rebels claimed Thursday they had captured the 120,000-barrel-per-day refinery in fighting that could be a turning point in the six-month civil war between Gadhafi and forces seeking to oust him.
    
The flow of crude to the refinery from fields in the southwest of Libya had largely been halted since midsummer and its capture was unlikely to have a major impact on Gadhafi's ability to secure fuel, but it was seen as a significant step in the rebel advance toward the capital.
    
Meanwhile, the International Organization for Migration said an operation to rescue "large numbers" of Egyptians and other foreigners, including a large group of journalists, from Tripoli will begin in coming days.
    
IOM spokeswoman Jemini Pandya said on Friday that the organization has appealed to donors for emergency funding to finance the evacuation, which was needed because the road between Tunisia and Tripoli has been closed.
    
"We have a very limited window of opportunity to carry out this operation because of the fighting, so it is essential that we are not constrained by a lack of funds from the outset," she told reporters in Geneva.
    
Explosions also shook the capital early Friday as NATO jets circled overhead. Flames lit up the Tripoli skies near Gadhafi's Bab al-Aziziya headquarters and army barracks.
    
Seven thunderous blasts could be felt at a hotel where foreign journalists stay in Tripoli. Residents also told the AP that three strikes hit the road to the airport in the capital.
    
In Tripoli, a government official said that NATO had killed the brother of Gadhafi's spokesman, Moussa Ibrahim.
    
The official said Hasan Ibrahim, 25, and others were struck by bullets fired from an Apache helicopter while on foot in Zawiya's central square.
    
The official, who spoke on condition of anonymity in line with government policy, said he did not yet have information on other casualties from the incident but accused NATO of killing civilians and providing air cover for rebels to advance on Libyan cities.

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