The Egyptian authorities, increasingly rattled by pro-reform protests, braced Tuesday for more demonstrations from opposition groups ahead of landmark elections. After hundreds of supporters of the prohibited Muslim Brotherhood movement demonstrated Sunday in defiance of a government ban, another opposition group called for a march in front of Parliament Wednesday. "Besides asking for a parliamentary republic, we will also march in support of civil liberties and freedom of expression," said the leader of Kefaya (enough) - a coalition group of leftists, liberals and Islamists.Noting the "growing nervousness of authorities in the face of mounting political dissent," George Isaac said he was "shocked by police repression on Sunday," during the Brotherhood's rally. Police deployed en masse Sunday to prevent the Brotherhood's supporters from reaching Parliament where the demonstration was originally set to take place. Positioned in compact squares, helmeted, shield-carrying and club-wielding forces managed to prevent any advances by the protesters. A few hundred marchers, asking for constitutional reforms and the lifting of restrictive emergency laws, managed to gather on the central Ramses Square, a mile away from Parliament, and in two other downtown spots. Fifty were arrested for having overlooked the government's demonstration ban, authorities said.