Police have arrested 50 members of the opposition Muslim Brotherhood group for organizing Gaza protests in Cairo, a security official said Monday. He said the arrests Monday followed calls by the outlawed Brotherhood on members and other opposition groups to stage more demonstrations to protest Israel's Gaza offensive. The official spoke on condition of anonymity because he is not authorized to speak to the media. Protests have taken place across Egypt since the Jewish state began its Gaza offensive Dec. 27. In some cases, police clashed with protesters and made arrests.