Sayf al-Islam said he was not at odds with his father
The son of Libyan leader Muammar Gaddafi has announced his retirement from political life.
Sayf al-Islam Gaddafi has been a leading proponent of reform through his charity, The Gaddafi Foundation.
He said he had been obliged to intervene politically, but this was no longer necessary, as Libya now had institutions and systems it had lacked.
He has previously denied reports he was being groomed to take power and said there was no rift with his father.
He has no official role in government but in the past four years he has come into the limelight internationally because of his interventions.
The BBC's Rana Jawad in the capital, Tripoli, says in an hour-long televised speech, Sayf al-Islam Gaddafi took some credit for the rehabilitation of Libya's reputation.
"I intervened extensively in everything: our foreign policy, in a lot of problems, in development, in housing. Because there were no institutions or an administrative system that were able to do so," he told a crowd in the desert town of Sebha.
"But now the situation has changed and if I continue there will be a problem."
He said the decision-making process should not be held in the hands of a few people and again urged the creation of more civil societies, an independent media and a judiciary enshrined in a new constitution.
These goals were the responsibility of all Libyans, he said, to a standing ovation in Sebha, where he was addressing a crowd of thousands of young supporters.
Sayf al-Islam is one of seven of Col Gaddafi's sons.
The Libyan leader's youngest son, Hannibal, has caused a diplomatic row with Switzerland after being charged with assaulting two of his servants last month.
Libya's state shipping company halted oil shipments to Switzerland in protest.