Egypt's banned opposition group the Muslim Brotherhood says more than 60 of its members have been detained in a new round-up by the security forces. It said the arrests had taken place in several parts of Egypt and included prominent members of the organisation.
The arrests come a day after the Muslim Brotherhood told Egyptians they should boycott a national referendum later this month on changing election rules.
The group says changes to presidential elections are only cosmetic.
Judicial sources quoted by AFP news agency said 56 Muslim Brotherhood members were seized on Tuesday, for "attempting to mobilise students and workers" against the government.
The opposition argues that proposed new rules allowing multi-candidate elections contain too many constraints for anyone to challenge incumbent President Hosni Mubarak.
Independent candidates need to have the backing of at least 65 members of the parliament, which is overwhelmingly dominated by the president's National Democratic Party.
The Muslim Brotherhood - the most popular opposition force in Egypt - is tolerated by the authorities but banned from operating as a political party.