Amnesty International has called for an independent inquiry into the circumstances of the death of Muammar Gadaffi after footage of his capture appeared to show that he had been summarily executed.
Footage broadcast by Arab satellite television stations showed the ousted Libyan leader being detained by Nato-backed rebels.
The footage shows Gaddafi bloodied and appearing fragile in the images, but he can be heard shouting at his captors as he is bundled towards a car.
Soon afterwards it is believed he was shot in the head.
Amnesty called for the National Transitional Council (NTC) to publish the full facts and hold a "full, independent and impartial inquiry to establish the circumstances of Colonel Gadaffi's death."
Foreign Secretary William Hague acknowledged that the footage appeared to show that Gadaffi was captured alive and then assassinated.
"Until we're sure I don't want to add to speculation. I agree that the footage does suggest that," he told Channel 4 News.
Meanwhile US President Barack Obama announced that the mission would "soon come to an end," lending further credence to the belief among many that the whole aim of the mission was one of regime change.
Nato met in Brussels on Friday to consider ending the seven-month Libyan air bombing, with Britain poised to withdraw all its estimated 1,000 RAF pilots, their support crews and Royal Navy personnel from the war-torn country.
Stop the War Coalition convenor Lindsey German said: "The aim always was to get rid of Gadaffi and they seem to have killed most of his family and supporters.
"I am dubious as to whether Nato and UK forces will leave, the bombing will stop but I'm afraid the Libyan people will find that unless Nato forces do leave now the government will end up doing the bidding of the Western powers whether it likes it or not."
Seeming to support that theory, Defence Secretary Philip Hammond announced on Friday that he expected British sales directors now to be "packing their suitcases" and heading off to Libya to "take part in the reconstruction" as soon as possible.
Ms German said: "Only one of Cameron's Tories could put it so crassly, but that is exactly what will be happening."
Foreign multinationals would be "all over Libya like they were in Iraq," she said.