At least seven loud explosions rocked the Libyan capital, Tripoli, early Friday as bombs fell in the vicinity of leader Moammar Gadhafi's main compound and several areas in the west of the city.

Opposition forces are now closing in on the capital from the west and the south, while NATO controls the seas to the north. Thousands of refugees are fleeing daily from Tripoli.

On Thursday, opposition fighters said they had seized complete control of the country's last functioning oil refinery in Zawiya, a town about 50 kilometers west of the capital. Residents say rebel forces control most of the town.

The rebels also said Thursday they had gained control of Sabratha, a coastal town west of Zawiya.

Meanwhile, the Libyan government has called for a cease-fire. Prime Minister Baghdadi Mahmudi told reporters in Tripoli that an end to what he called NATO airstrikes on the Libyan people was the first step in ending bloodshed.

On Wednesday, fresh clashes erupted between pro-Gadhafi forces and rebels on the eastern front in the strategic city of Brega. Rebels said 18 of their fighters were killed and at least 33 had been wounded on Tuesday.

Meanwhile, the U.S. military deployed two more armed Predator drones for surveillance operations over Libya, where opposition fighters remain heavily dependent on NATO air power.