Anti-Gadhafi fighters stand guard at an area that they have taken control as their forces capture main landmarks in Sirte October 9, 2011. [Photo/Agencies]

TRIPOLI - As its forces fiercely attacked fallen Libyan leader Muammar Gadhafi's last two bastions, Sirte and Bani Walid, the interim government claimed Sunday the fighting could end next week.

The head of the National Transitional Council (NTC) Mustafa Abdel-Jalil said the battles in Bani Walid, some 180 km south of the capital, had entered its "last phase," with fighters laying siege to the town from all sides.

An NTC commander in the region said the same day NTC fighters had taken over Bani Walid's airport, which has been a stumbling block for the attackers due to its difficult geography.

Jalil also confirmed the NTC's unremitting assaults on Gadhafi's hometown, Sirte, about 450 km east of Tripoli.

The fight has been a bloody one with the local hospital saying Saturday at least 18 people were killed and about 300 wounded in two days since October 7.

After seizing a key road Saturday, the NTC made further major progress Sunday by taking control of the Ouagadougou conference center in downtown Sirte, a focus of heavy fighting in recent days, and a hospital and a university at the main entrance to southeastern Sirte.

Jalil said the fighters were still trying to root out pockets of Gadhafi loyalists and the many snipers, who are reportedly shooting indiscriminately at anything that moves on the street.

Meanwhile, the United States and its NATO allies were considering an end to its six-month bombing campaign that has backed the successful rebel push against Gadhafi.

U.S. defence secretary Leon Panetta said in Naples Thursday NATO was weighing whether to halt their air strikes, adding it would greatly depend on NTC's ground forces in the region.

He also said NATO would keep striking until Gadhafi's loyalists laid down their weapons and the interim government secured the whole country.

Panetta raised a four-point guideline for halting the raids, including Sirte's situation, an end to Gadhafi forces' attacks on civilians, ending his ability to command fighters and the NTC securing the country.

However, on the same day, the Syria-based Arrai television released an audio message from the ousted Libyan leader, who has remained at large since NTC forces entered Tripoli on August 23.

Gadhafi called on Libyans to take to the streets in their millions with their green flags peacefully and bravely, saying the current conditions in Libya were "unacceptable."

He also warned leaders of the developing countries who had recognized the NTC would face a similar fate as him.

Meanwhile, the humanitarian situation in Sirte has worsened, with civilians fleeing in panic in the face of the bombardment by NTC forces and NATO air strikes and heavy casualties among NTC fighters and Gadhafi loyalists.

The UN issued a statement Friday calling for no revenge attacks in Sirte if it is captured by the Libyan interim government while NATO Secretary General Anders Fogh Rasmussen said he believed NTC forces "will do all they can to prevent a humanitarian disaster."