Reuters reports:

Libyan rebels took control of an oil refinery in the western town of Zawiyah and blocked the main highway north to the capital on Thursday, further isolating Muammar Gaddafi’s Tripoli stronghold.

Rebel advances in recent days have cut Gaddafi’s forces off from their main resupply routes following a months-long stalemate, putting the Libyan leader’s 41-year rule under unprecedented pressure.

Small groups of rebel fighters occupied the inside of the Zawiyah refinery complex, about 50 km (30 miles) west of Tripoli along the highway linking Tripoli to Tunisia, with no sign of the pro-Gaddafi forces that had battled for the plant.