Fighters loyal to Libya's transitional government Sunday claimed major advances in Sirte and Bani Walid, the last strongholds of fugitive leader Moamer Gaddafi, dpa reported.
The pro-rebel Libya Free TV said they had seized a main conference hall in the centre of Gaddafi's hometown of Sirte where the ousted leader used to host Arab and African gatherings.
They also captured the city's university and arrested dozens of pro-Gaddafi snipers.
Anti-Gaddafi forces also seized Sirte's central hospital, from where Gaddafi diehard loyalists had been coordinating their fighting plans.
"The road is now open for fully controlling Sirte," said Mahmoud al-Fayad, a military commander loyal to Libya' interim leaders.
Earlier on Sunday, interim authority forces told broadcaster Al Jazeera that they had arrested Abdel Rahman Abdel Hamid, a nephew of Gaddafi and a chief of a pro-Gaddafi security brigade in the port city.
Abdel Hamid, who was being kept in a camp belonging to the rebel forces, had provided "important" information during preliminary investigations, the Free Libya TV said.
Since the early hours of Sunday, anti-Gaddafi forces had set up checkpoints around Sirte to prevent Gaddafi loyalists from fleeing the city.
They believe that senior officials in the former regime, including Gaddafi's son Mutassim, are still hiding in the city located on the Mediterranean coast.
Anti-Gaddafi forces also launched an attack on Bani Walid, a mountainous town located 400 kilometres south-east of the capital Tripoli, where they seized control of parts of the airport and were still engaged in battling "pockets of resistance," Al Jazeera reported.
Commanders loyal to the country's interim leaders were negotiating with tribal chiefs in Bani Walid to allow their troops to enter the town peacefully.
Military reinforcements were, meanwhile, sent to the outskirts of the town to support the anti-Gaddafi forces if negotiations failed, according to commanders in the interim authorities.
Previous bids to capture Bani Walid had failed due to stiff resistance from pro-Gaddafi fighters.
Libya's transitional rulers have delayed announcing a new government until the whole North African country is "liberated."