The international police agency, Interpol said in a statement on Thursday that it has issued a red notice for al-Saadi Gaddafi, based on a request by the National Transitional Council, the opposition movement whose fighters overthrew Gaddafi last month.
It was the first time Interpol has issued such a notice at the request of Libya's post-Gaddafi leadership.
Interpol says the notice was based on accusations that al-Saadi Gaddafi, 38, misappropriated property and engaged in "armed intimidation" when he headed the Libyan Football Federation.
He was also a special forces commander and is the subject of UN sanctions for commanding military units involved in repression of demonstrations.
Al-Saadi and other Gaddafi regime loyalists have crossed into Niger earlier this month following former rebel advances on loyalist areas.
Interpol urged authorities in Niger and surrounding countries, and countries with direct flights to Niger, to watch out for and arrest Gaddafi "with a view to returning him to Libya" for prosecution.
Interpol's red notices are the highest-level alerts they can issue to their member countries. The notices do not force countries to turn over suspects but strongly urge them to. Countries that ignore such notices can come under pressure from the international community.
Interpol has already issued red notices for Muammar Gaddafi and his son Seif al-Islam Gaddafi based on a request by the International Criminal Court. Both men have been charged with crimes against humanity.
Muammar Gaddafi's whereabouts are unknown. Libya's new rulers said Wednesday they believe he may be hiding in the southern desert under the protection of ethnic Tuareg fighters, while two of his other sons are holed up in cities besieged by revolutionary forces elsewhere in Libya.
Gaddafi's wife and daughter fled to neighbouring Algeria.