Anti-Gaddafi forces 'seize Sirte'
Libya's transitional government forces have taken full control of Sirte, the last city where Gaddafi loyalists had remained holed up, fighters and reporters say.
Soldiers hoisted the new NTC national flag on buildings in the centre of Col Muammar Gaddafi's hometown.
Unconfirmed reports quote officials as saying Col Gaddafi was captured there.
His supporters are still resisting government forces in the town of Bani Walid, south-east of Tripoli.
The BBC's Gabriel Gatehouse on the outskirts of Sirte - about 360km (220 miles) east of the capital - says he cannot confirm that the town has fallen.
Troops at roadblocks set up around the town say their purpose is to prevent a mass break out by pro-Gaddafi forces.
Officials in Tripoli sent mixed messages about the situation. A military spokesman said Sirte had been "almost liberated".
Sirte is the big prize. It was Col Gaddafi's birthplace and hometown - the place he turned from a small village into essentially his second capital. The forces loyal to the new authorities have been fighting very hard for it for two months now since Tripoli fell.
It is politically very important because the authorities have said that when Sirte falls they will declare full victory, full liberation of the country, and that starts a countdown of a political process that should lead to full elections within two years.
We know that large numbers of the forces fighting for the new authorities have been killed. Much harder is to know what the toll has been on the other side, and also on the civilian side. If this is the fall of Sirte - and commanders on the ground think it is - it has come at a very high price.
But Abdel Hakim Belhaj, the military commander of the National Transitional Council (NTC) in the capital, said: "We, thank God, announced that [Sirte] has been liberated."
There are reports that senior figures in Col Gaddafi's former regime have been captured or killed.
The fall of Sirte, if confirmed, represents a very significant moment in the overthrow of Col Gaddafi.
The NTC has said that this would be the point at which it would declare Libya liberated. The transitional authorities have said a new government would then be formed within a month, and the current administration would resign.
The head of government operations in the eastern half of the city told Reuters news agency on Thursday: "Sirte has been liberated."
"There are no Gaddafi forces any more," Col Yunus al-Abdali added. "We are now chasing his fighters who are trying to run away."
At least 16 pro-Gaddafi fighters were captured, along with ammunition and trucks loaded with weapons, the Associated Press reported.
NTC fighters celebrated by firing in the air, and chanting "Allah akbar" ("God is great"), AP reported.
The NTC had been facing heavy resistance from snipers in the city, and used heavy artillery during its offensive. Thousands of civilians have fled.
Government forces have also suffered heavy casualties in Bani Walid in recent weeks.
On Monday the NTC said it had captured 90% of the town, including the centre.
Col Gaddafi, who ruled Libya for 42 years, was ousted in August, when rebel forces captured Tripoli.
His whereabouts remain unknown. Several of his family member are in hiding or have fled the country.