Saif al-Islam Gaddafi recently said he was stepping back from politics
Libya has freed more than 200 Islamist inmates as part of its programme of rehabilitation of militant groups.
It was "an historic event", said Col Muammar Gaddafi's son Saif al-Islam, whose Gaddafi Foundation has tried to engage with Islamists in recent years.
Some 34 of the 214 freed inmates are from the Libyan Islamic Fighting Group, which has suspected links to al-Qaeda but has reportedly renounced violence.
In the past, the group has been accused of trying to oust Col Gaddafi.
Three of the group's leaders were among those released.
"With the release of these leaders, we have brought to a conclusion our programme of dialogue and reconciliation," Saif al-Islam Gaddafi was quoted as saying by AFP news agency.
Dozens of the group's members went free last year after talks with Tripoli to reach a deal to renounce violence.
"We are at the point of bringing to an end a tragic period," Mr Gaddafi said.
He said that 165 security officers had been killed in clashes with the Islamists over the years, while 177 insurgents had also died.
The rehabilitation programme had led to the release of 705 Islamists, he said.
Some 409 remained in prison. A further 232 would be set free soon, Mr Gaddafi added.
In a news conference, Mr Gaddafi called on Libyans currently fighting in Algeria and in the deserts of Mali to lay down their arms, saying they could come back to Libya as free people and reintegrate as productive citizens.
The BBC's Rana Jawad in Tripoli says there are still many unanswered questions - not least about what guarantees there are that former militants will not simply take up arms once again.