The city had been held by troops loyal to the embattled Libyan ruler Muammar Gaddafi since the revolution began more than two weeks ago but fell into the hand of protesters on Saturday.
Opposition forces also say they have downed two helicopters belonging to the forces loyal to Colonel Gaddafi near Ras Lanuf and Ben Jawad.
Revolutionary fighters are in control of the oil-rich city of Ras Lanuf. They captured the city after heavy fighting, which reportedly left at least eight people dead.
These latest developments come as reports of fresh fighting have emerged from Libya's western city of Zawiyah.
Heavy gunfire can be heard with pro-Gaddafi tanks firing at houses in Zawiyah, 50 kilometers from the capital, Tripoli.
Witnesses say opposition forces have set pro-Gaddafi tanks on fire and arrested a number of their forces.
This comes a few hours after the opposition repelled an attack by pro-Gaddafi forces to retake the city.
At least 30 people, including women and children, have been killed.
Meanwhile, in Benghazi, dozens of people were killed and many more were wounded after the government forces used warplanes to bomb a weapons depot near the city.
Protest rallies have spread to Tripoli, which is Gaddafi's stronghold. Clashes erupted in the city after Gaddafi's loyalists fired teargas to disperse demonstrators.
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