His captors, the Abu Bakr Al Siddiq Battalion, released a statement at the weekend saying that Gaddafi had been released on Friday, the Voice of America (VOA) reported on Sunday.
However, no details were given of Gaddafi’s whereabouts on the grounds of fearing for his safety.
The captors said the release was decided as part of a recent pardon issued by the Libyan parliament based in the country’s eastern region.
Tobruk’s parliament is one of three rival administrations in Libya as chaos and war continue to ravage the North African country following Muammar Gaddafi’s overthrow and death during the 2011 revolution after 40 years in power.
The late dictator’s son was captured by the Abu Bakr Al Siddiq Battalion in 2011.
During the uprising, Seif Al Islam led Gaddafi’s forces against rebels fighting to overthrow his father.