Photo of Sayf al-Gaddafi courtesy of the BBC
Sayf al-Islam Gaddafi also called for a national dialogue on a new constitution to strengthen Libya's political system.
But he said Islamic Sharia law, security issues, Libya's territorial unity and his father's leadership would be kept out of any political debate.
Sayf al-Islam holds no government post, but is his father's most trusted envoy.
He has denied reports that he is being groomed to succeed his father.
'People's contract'
In a speech broadcast live on state media, Mr Gaddafi said the current political system, which mixes Islamic ideas with some socialist principles, was flawed.
He said it criminalised political dissent and banned the creation of political parties and a freely-elected parliament. Gaddafi son unveils reform plan (more)
Mark Alexander
