Police arrested 400 Muslim Brotherhood activists in a crackdown on the Islamist group which poses the strongest challenge to the ruling party in Egyptian legislative elections on Sunday.
Armed thugs also attacked Brotherhood supporters and blocked them from voting in the second stage of elections which will decide 144 seats in parliament, election monitoring groups said.
Brotherhood candidates doubled their strength in parliament in the first stage of the elections, winning 21 percent of the 164 seats contested and underlining the strength of political Islam as Egypt's strongest opposition force. The ruling National Democratic Party (NDP) won 68 percent of the seats.
The authorities had given the Brotherhood, banned since 1954, unprecedented leeway in the weeks leading up to the first stage. Leading Brotherhood member Essam el-Erian said the authorities had fallen back on their old ways.
"This indicates the lack of any intention by the government or the regime to meet the promises it made to make real political or constitutional changes," he told Reuters.
Violence was limited in the first stage but spread on Sunday. Gangs, primarily made up of NDP supporters, controlled access to polling stations and threatened voters, the Independent Committee on Election Monitoring said.