Fresh fighting between government and rebel forces has entered its fourth day, in the strategic Libyan city of Brega. At least 127 opposition troops were injured during Sunday's clashes. And in Tripoli, NATO aircraft have destroyed a military storage facility, along with several other targets on the capital city's eastern outskirts.

Fighting between gov't and rebels injures 127.

In the biggest offensive in eastern Libya in weeks, rebel forces have entered the oil port of Brega, and fought fierce street battles there with embattled leader Muammar Gaddafi's military.

Opposition officials say the urban warfare has injured more than 120 insurgent troops.

But they add that the northeast quadrant of the city has been taken, and a campaign is also underway against government forces holed up in the southwest sector.

Brega, located some 750 kilometers east of Tripoli, is the site of a strategic petroleum terminal.

The area has changed hands several times during the back-and-forth conflict along Libya's Mediterranean Coast, since the unrest began in February.

The latest attack could signal a new rebel push westward, from the main opposition stronghold in eastern Benghazi, after weeks of stalemate.

Meanwhile, NATO reports flying more than 100 sorties, and carrying out at least 40 strikes over Tripoli on Saturday.

The alliance says its forces have hit a weapon storage facility, along with three radar sites and an anti-aircraft missile launcher, east of the capital.

Muammar Gaddafi is still refusing to step down, despite five months of strife against his administration.

The slow progress of the insurgent military campaign has caused strains within NATO. Several member states are pressing for a negotiated solution, to bring a swift end to the conflict.