Information Minister Mahmoud Shammam said fighters had told him they had seen Col Gaddafi’s body, and other officials also said he was dead.
The claims have not yet been independently verified, and other reports said he was captured alive.
The colonel was toppled in August after 42 years in power.
The International Criminal Court has been seeking his arrest.
Golden gun Nato, which has been running a bombing campaign in Libya for months, said it had carried out an air strike earlier on Thursday that hit two pro-Gaddafi vehicles near Sirte.
It was unclear whether the strikes were connected with the reports of Col Gaddafi’s death.
Mr Shammam said NTC leaders would officially confirm Col Gaddafi’s death later.
“He was killed in an attack by the fighters. There is footage of that,” he said.
Grainy video footage has been circulating among NTC fighters appearing to show Col Gaddafi’s corpse.
The video shows a large number of NTC fighters yelling in chaotic scenes around a khaki-clad body, which has blood oozing from the face and neck.
NTC official Abdel Hafez Ghoga told AFP: “We announce to the world that Gaddafi has been killed at the hands of the revolution.
“It is an historic moment. It is the end of tyranny and dictatorship. Gaddafi has met his fate.”
An NTC fighter told the BBC he found Col Gaddafi hiding in a hole in Sirte, and the former leader begged him not to shoot.
The fighter showed reporters a golden pistol he said he had taken from Col Gaddafi.
Arabic TV channels showed images of troops surrounding two large drainage pipes where the reporters said Col Gaddafi was found.
NTC supporters gathered in towns and cities to celebrate the reports of the colonel’s death.
Groups of young men fired guns in the air, and drivers honked horns in celebration.
His apparent death came after weeks of fierce fighting for Sirte, one of the last remaining pockets of resistance.
At the scene
Driving into the centre of Tripoli, there are throngs of people out on the streets – men, women and children – many hugging each other and chanting. Gunshots can be heard firing into the air – despite a religious edict banning the practice. Car horns are blaring and many vehicles have their emergency lights blinking.
At some checkpoints, security officials are handing out what have been dubbed “revolutionary mints” and biscuits.
All the flags are out. People are genuinely convinced this is the end of Col Gaddafi. They felt that even in hiding he posed a threat to the revolution – but for them this news means the authorities can now start to rebuild the country.
NTC official Abdel Hafez Ghoga told AFP: “We announce to the world that Gaddafi has been killed at the hands of the revolution.
“It is an historic moment. It is the end of tyranny and dictatorship. Gaddafi has met his fate.”
An NTC fighter told the BBC he found Col Gaddafi hiding in a hole in Sirte, and the former leader begged him not to shoot.
The fighter showed reporters a golden pistol he said he had taken from Col Gaddafi.
Arabic TV channels showed images of troops surrounding two large drainage pipes where the reporters said Col Gaddafi was found.
NTC supporters gathered in towns and cities to celebrate the reports of the colonel’s death.
Groups of young men fired guns in the air, and drivers honked horns in celebration.
His apparent death came after weeks of fierce fighting for Sirte, one of the last remaining pockets of resistance.
Source: http://www.bbc.co.uk/news/world-africa-15389550
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It’s never good when you have to kill someone. Perhaps if he had been nicer to his people, this wouldn’t have had to end this way. Now Libya can rebuild itself into a much more respectable nation.