campaign group human right watch friday condemn arrest saudi authorities 30 clerics intellectuals activists week coordinate crackdown dissent amnesty international echo sentiment arrest make exile opposition figure call demonstrations follow friday afternoon prayers appear attract much support amid heavy security deployment activists week circulate social media list people detain include prominent islamist preacher salman al-awdah well people clear link islamist activity obvious history opposition detentions come amid widespread speculation deny officials king salman 81 intend abdicate favor son crown prince mohammed dominate economic foreign domestic policy also grow tensions qatar allege support islamists include muslim brotherhood list riyadh terrorist organization apparently politically motivate arrest another sign mohammed bin salman real interest improve country record free speech rule law say sarah leah whitson middle east director human right watch new york-based group say arrest fit pattern human right violations peaceful activists dissidents include harassment intimidation smear campaign travel ban detention prosecution crown prince mohammed rocket pinnacle power kingdom push reform agenda call vision 2030 aim wean country oil introduce social reform critics say enough liberalize politics country king enjoy absolute authority amnesty international also denounce crackdown urge authorities reveal whereabouts detainees give access families lawyers recent years recall week many prominent saudi arabian figure target short space time say samah hadid group director campaign middle east clear new leadership crown prince mohammed bin salman send chill message freedom expression tolerate come government spokesman immediately respond request comment public protest ban saudi arabia political party labor unions illegal media control criticism royal family lead prison riyadh say political prisoners senior officials say monitor activists need maintain social stability al-saud family always regard islamist group big internal threat rule country appeal religious sentiment lightly dismiss al qaeda campaign decade ago kill hundreds islamist movements muslim brotherhood originate egypt briefly hold power 2011 arab spring represent ideological threat saudi arabia dynastic system rule brotherhood-inspired sahwa movement agitate 1990s bring democracy saudi arabia criticize rule family corruption social liberalization work west include allow u.s. troop kingdom 1991 iraq war sahwa weaken mixture repression co-optation remain active saudi arabia unite arab emirates bahrain egypt cut diplomatic transport link qatar june allege support islamists include brotherhood charge doha deny mosque central riyadh protest organizers identify one several potential gather spot imam warn worshippers demonstrate group exist today call political action aspire rule misguide deviant group head muslim brotherhood say people seem heed message demonstrations report across kingdom right group condemn saudi arrest crackdown dissent