Libyan rebels plan on advancing toward Zawiyah, which would put them within striking distance of Tripoli  [AFP]

Libyan opposition fighters have reportedly captured several residential districts of Brega, a strategic city for Muammar Gaddafi's government.

Speaking on Thursday, Mossa Mahmoud al-Mograbi, a spokesman for the rebel forces, said: "It is liberated. It is under our control now."

But another opposition spokesman Mohammed Zawawi told reporters it was still not safe to go into the city. The oil terminal is about 15kms from the residential district.

"Now we're trying to clear that area. There are some Gaddafi troops still there," Zawawi said. "Gaddafi troops are shooting rockets into the city."

Sources told Al Jazeera that the rebels had suffered 40 casualties, including seven dead. They also said that 12 Gaddafi soldiers had surrendered.

Brega's western half, where its oil facilities are located, remains in the control of Gaddafi's forces.

Rebels hope that if they are able to take complete control of the city its oil terminal and sea port will allow them to resume oil exports.

Al Jazeera's Andrew Simmons, reporting from Misrata, called the rebel advances "very important and very significant".

Simmons said "it's definitely a move forward", but whether or not these gains remain is "subject to securing areas" and if "there's going to be a counter-offensive".

An area south of Brega was also captured by the rebels on Thursday, though clashes are ongoing.

"We are sure we will defeat them," said Mograbi.

The gains in Brega come as Libyan rebels continue their push north toward the town of Zawiyah.

Their aim is get within striking distance of Tripoli, the nation's capital and headquarters of Gaddafi.

The embattled leader has clung to power despite five months of NATO air strikes, suffocating economic sanctions and an expanding war with opposition forces.

Source: Al Jazeera and agencies