Libya's Colonel Muammar Gaddafi was killed in crossfire after being captured in his birthplace of Sirte, officials say.

A Libyan spokesman quoted “After 42 years, Col Gaddafi's rule of fear has finally come to an end. I call on all Libyans to put aside their differences and work together to build a brighter future."

Acting Prime Minister Mahmoud Jibril said Gaddafi had been shot in the head in an exchange between Gaddafi loyalists and National Transitional Council fighters.

He confirmed that Col Muammar Gaddafi, who had been taken alive, had died before reaching hospital.

Mr Jibril, number two in the National Transitional Council (NTC), held a news conference in Tripoli to confirm the colonel's death.

"We have been waiting for this moment for a long time. Muammar Gaddafi has been killed," he said.

Later, Mr Jibril told journalists that a "forensic report" had concluded that the colonel had died from bullet wounds after he had been captured and driven away.

"When the car was moving it was caught in crossfire between the revolutionaries and Gaddafi forces in which he was hit by a bullet in the head," he said, quoting from the report.

The man who claims to have shot Gaddafi 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.

US President Barack Obama said it was a "momentous day" for Libya.

By Cliona Gordon