A U.S. rights watchdog has lambasted Egyptian police for inciting the sexual abuse and thrashing of demonstrators during a referendum this week and urged President Hosni Mubarak to investigate the "state-sanctioned brutality." "Plainclothes security agents beat demonstrators, and riot police allowed - and sometimes encouraged - mobs of Mubarak supporters to beat and sexually assault protesters and journalists," Human Rights Watch (HRW) said of Wednesday's crackdown on anti-referendum rallies.