Libya's interim leader Mustafa Abdel Jalil said today that a commission of inquiry is to probe the controversial killing of ousted leader Muammar Gaddafi.

"In response to international calls, we have started to put in place a commission tasked with investigating the circumstances of Gaddafi's death in the clash with his circle as he was being captured," Abdel Jalil said.

He said all Libyans "wanted to try (Gaddafi) for what he has done to them. From executions, to imprisonment, to throwing away the Libyan wealth ... or using that wealth against the Libyan people."

"Some people may have wanted him to have been tried to extend their feeling of relief at his downfall," said Abdel Jalil, who is the leader of the National Transitional Council.

"Free Libyans wanted Gaddafi to spend as much time in prison as possible and feel humiliation as much as possible," he added.

Disquiet has grown internationally over how Gaddafi met his end after NTC fighters hauled him out of a culvert where he was hiding following NATO air strikes on the convoy in which he had been trying to flee his falling hometown on Thursday.

NTC leaders, including Abdel Jalil, are adamant he was shot in the head when he was caught "in crossfire" between his supporters and new regime fighters soon after his capture.

"Those who had interest in his speedy death were the ones who supported him," he said. "His speedy death would have been in their interest."

During his press conference Jalil also sought to dispel fears that the North African nation would adopt hardline Islamic rule, a day after he declared sharia law the primary source for future legislation.