Egyptian officials have ordered police on alert to foil a nationwide strike planned by pro-democracy activists for Monday.
Sunday's measures came a day after police arrested 28 activists of the April 6 Movement, which had called for the strike to protest government restrictions.
Officials say plainclothes security men were deployed in Cairo's main squares and around several government offices where the activists say they will stage their protests. The officials spoke on condition of anonymity because they are not allowed to make statements.
On Saturday, a court in the Nile Delta town of Kafr el-Sheikh ordered two female students detained after they handed out pamphlets calling on people to join the April 6 strike.
The Muslim Brotherhood, Egypt's largest opposition group, said it would take part in the strike.