Libya’s interim government fighters have been bombarding the city of Sirte while NATO warplanes are reported to have carried out bombing raids on the Gaddafi stronghold.
It is a hugely symbolic target, being the birthplace of the deposed leader. But that also makes it a difficult task for the rebels, since loyalists in the town are said to be well-armed, and many people living there have family and tribal ties to Gaddafi.
It is not known if he or any of his family are in the city.
Elsewhere Gaddafi troops showed they are still a threat by attacking the desert oasis town of Ghadames near the Algerian frontier.
Officials say at least five NTC soldiers were killed in the attack.
In Tripoli the interim authorities say they found a mass grave containing the bodies of more than 1200 people killed by the former regime in a 1996 massacre at Abu Salim prison.
The uprising in Libya was in part ignited by protests linked to the events at the prison.
In February thousands of families of the victims demonstrated to demand the release of their lawyer.