Egyptian prosecutors on Thursday extended the detentions of 79 members of the Muslim Brotherhood, including four group leaders, arrested in a government crackdown sparked by a wave of pro-reform protests by the banned Islamic movement. A total of 754 group members have been detained because of the protests, which the group has held in several Egyptian provinces during the past month as part of a growing opposition campaign for reform. The 79 group members were ordered held for another 15 days for further investigation, prosecution officials said. The four leaders — including Essam el-Eriyan, one of the movement's most prominent members — were arrested May 6 for belonging to a banned organization and organizing unauthorized protests. Under emergency laws imposed in 1981, suspects can be detained up to six months without trial.