Libyan rebels take control of an oil refinery in the town of Zawiyah just thirty miles west of the capital Tripoli, in a strategic and psychological blow to Colonel Gaddafi's forces.

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After nearly a week of intense fighting the rebels have advanced from their western mountain bases near Tunisia and have taken the sea-side complex of Zawiyah which lies along the main western coastal highway linking Tripoli with Tunisia.

Rebel fighters say 150 Gaddafi troops later fled the area on Zodiac boats, following a battle that has reportedly killed at least nine people and injured 45, most of them rebels.

But some analysts said the capture of the 120,000-barrel-per-day refinery in Zawiyah would not have a major impact on Gaddafi's ability to secure fuel.

"In that sense, it's more significant that they [the rebels] have got control of the roads than the refinery," said John Hamilton, a contributing editor of Africa Energy.

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"Strategically, that's a more important gain for the rebels. Having control of the roads makes it much harder for Gaddafi to get the petrol he needs from Tunisia and Algeria."

Opposition forces also controlled the town of Garyan, which lies on a main highway fifty miles south of Tripoli.

Reuters reported that a rebel T-34 tank and an anti-aircraft gun seized from Gaddafi forces was in place in the main square in Garyan.

This is a crisis that will last a few days and then it will be - God willing - overcome, Mussa Ibrahim, Gaddafi spokesman

"We took one tank and an anti-aircraft gun from Gaddafi's forces. Next, we will go to Tripoli," said one of the fighters, who called himself Mohammad.

It means the rebels are closing in on the capital from the west and the south, while NATO controls the seas to the north of Tripoli, which sits on the Mediterranean coast.

The spokesman for Gaddafi played down recent rebel gains and said the government remained in control of the country.

"This is a crisis that will last a few days and then it will be - God willing - overcome," said Mussa Ibrahim in remarks carried by JANA news agency on Thursday.

"We will push ahead and until we liberate the whole country," Ibrahim added.

Eastern front

On the eastern front, rebel forces said they had tightened their grip around the oil town of Brega, but had suffered high casualties in fighting over the past several days.

About 40 rebels have been killed and nearly 100 wounded in and around Brega over the past 10 days, according to a tally of reports from the rebels and hospital workers.

"All of Alargop is now free, liberated," spokesman Musa Mahmoud al Mugrabi said of the area six km south of Brega, which is on a supply route for Gaddafi's forces running south.

Libya's rebel National Transitional Council (NTC) has denied holding secret talks with Gaddafi to end the war. But suspicions persist that some form of end-game negotiation may be going on.

Meanwhile in opposition-held Misrata, which lies 100 miles east of Tripoli, rebels say they have uncovered a mass grave containing 150 civilian bodies.

"We discovered a mass grave containing 150 bodies in Tawargha. These are the corpses of civilians kidnapped from Misrata by Gaddafi's loyalists," an unamed rebel spokesman told Reuters. He also claimed rebels have found a video "showing kidnappers cutting the throats of people".

The spokesman said rebel forces were now outside a place called Hisha about 100 km (60 miles) west of Misrata on the road to Tripoli.