Egypt's top prosecutor on Saturday issued a release order for political activist Ahmed Maher, reported Al Jazeera.

Maher, a founding member of the opposition youth movement April 6, was detained at the airport upon his return from the United States of America on Friday.

Authorities at Cairo International Airport had placed him on the airport's watchlist, according to sources.

Maher was detained for allegedly protesting outside the house of the Interior Minister Mohamed Ibrahim while dressed in his underwear in March, a source told Reuters News Agency.

"April 6" is an opposition movement that played a vital role during the 2011 popular uprising that ousted former president Hosni Mubarak.