Political activist Ahmed Douma - photo from his Facebook page
Scores of protesters rallied in front of Beheira's security directorate to demand that the ministry reveal the location of activist Ahmed Douma on Wednesday.
Douma had been arrested and detained for four days pending investigation on charges of insulting President Mohamed Mursi.
Demonstrators from the Democratic Front Party and the Arab Revolution Youth Movement gathered at the security directory and chanted slogans demanding to know Douma's whereabouts.
Douma was also charged with spreading false information likely to disrupt public order and harm public interest.