Muammar Gaddafi has been killed in Libya.

Muammar Gaddafi has been killed in Libya. ( News source BBC)

After a day of conflicting reports and rumours, Mr Jibril told the news conference: "We have been waiting for this moment for a long time. Muammar Gaddafi has been killed."

Al-Jazeera TV broadcast footage it says showed Col Gaddafi's body

World leaders welcomed the news, urging the NTC to carry through its promise to reform the country.

UK Prime Minister David Cameron, who had taken a leading role in the Nato intervention, said it was "a day to remember all of Col Gaddafi's victims".

UN Secretary General Ban Ki-moon called it a "historic" moment, but warned: "The road ahead for Libya and its people will be difficult and full of challenges."

Earlier, grainy video footage circulated 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.

Another video broadcast by al-Jazeera TV showed a body being dragged through the streets which the channel said was that of Col Gaddafi.

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.

'Saif surrounded'

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 death came after weeks of fierce fighting for Sirte, one of the last remaining pockets of resistance.

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 Col Gaddafi's death.

Mr Jibril promised that National Transitional Council (NTC) chief Mustafa Abdul Jalil would give more details of how Col Gaddafi was killed either late on Thursday or during Friday.

He said Mr Abdul Jalil would also officially announce the "liberation of the country", allowing the NTC to begin pushing through democratic reforms that will lead to elections.

"I think it's for the Libyans to realise that it's time to start a new Libya, a united Libya, one people, one future," Mr Jibril said.

He also told the news conference that NTC forces had surrounded Saif al-Islam's convoy.

There are also rumours that another of the colonel's sons, Mutassim, was killed in Sirte.