[JURIST] Mahmoud Ezzat, secretary-general of outlawed Egyptian opposition group Muslim Brotherhood [official party website, in Arabic], was arrested by Egyptian authorities early Sunday. Egyptian police say that Ezzat, the fourth ranking member of the Brotherhood, is the highest profile member arrested since 1996. Authorities claim that the arrest is a warning to all opposition groups who are opposed to the new rules governing the first multi-candidate election in Egypt [JURIST report]. Opposition parties have announced that they will boycott the upcoming referendum [JURIST report] when the public votes on the proposed constitutional amendment [JURIST report] due to their belief that the amendment only favors President Hosny Mubarak [official profile]. Mubarak has been re-elected for the past 24 years by a referendum on which he was the sole candidate. The amendment proposes rules that would restrict many officials from opposition parties from running in the upcoming election [JURIST report], including jailed militant and Muslim Brotherhood candidate Essam el-Erian [Al Ahram profile/interview]. Over 800 Brotherhood members have been detained for involvement in recent Egyptian protests concerning the referendum. AP has more.